On a Southworth LS-Series hydraulic lift table, the manufacturer's own troubleshooting list runs from an over-heavy load to the motor's power supply, then on to oil level, tank vent, suction filter and last the upper limit switch. A failed cylinder is not on that list. So when the platform stops coming up, the order to work in is load first, power second, hydraulics third, and the point of that order is to rule out a whole branch with one cheap check instead of guessing at the most expensive part.
That order holds for the LS-Series as documented on the manufacturer's product page, and it stops holding at one identifiable point. If the load is at or below the rating, the motor runs, the oil sits at the level that matches the platform's position, the vent plug is in and the suction filter is clean, and the table still will not raise, then none of the checks below applies any longer and the table belongs with qualified service rather than with a parts order.
The Cylinder Is Not Where This Starts
The listed causes fall into three groups rather than one flat list. Two of them belong to the power branch, the motor not running at all and the motor humming without turning, and four belong to the hydraulic branch, oil level, tank vent, suction filter and a vacuum leak at the suction line. The last item, the upper limit switch, is not a failure at all but a stop condition, and it explains only one symptom.
Ordering by cost is what makes the sequence defensible. Each check is cheap, needs no parts and eliminates a whole branch, so a table that fails one of them never has to be diagnosed any further. If the motor is silent when the button is pressed, stay on the power branch and skip the oil question completely. When the motor runs and the platform still does not move, skip the electrical checks and go straight to the hydraulic side. A platform that halts at the same height every cycle is a stop condition, so leave both branches alone until the limit switch has been ruled out.
Is the Load Over the Table's Rating?
The LS-Series page puts one item ahead of every electrical and hydraulic cause: the weight of the load must be at or below the maximum allowed, so the actual weight has to be confirmed rather than assumed from what the pallet is supposed to hold. It is the only listed cause that costs nothing to verify and the only one that no part purchase can cure. A new motor on an overloaded platform changes nothing, and a cleaned suction filter under a load that is too heavy changes nothing either.
Practically, that means the weight question is answered before a purchase order is written, not after. If the load is over the rating, go with fixing the load, splitting the pallet or changing what the table is asked to lift, and not with repairing the table. A load under the rating closes this cause and moves the next branch to the motor's power supply.
Nothing Happens When You Press the Button
A completely silent motor narrows things quickly. The manufacturer's list for that symptom is the main disconnect switch, the fuses and the wiring to the motor, and the same page notes that a 20 amp designated breaker must be supplied for 110V. Those are panel-level items, and the sensible split in a working warehouse is that the person the site authorizes for that panel checks them while everyone else stays out of it.
The trade-off is about where to spend the next hour. An open disconnect or a blown fuse means going with the supply-side fix and skipping the hydraulic checks entirely, because nothing downstream can be tested on a table with no power. With the disconnect and fuses intact and the 110V circuit on its designated 20 amp breaker, the hydraulic branch is still not implicated, since a silent motor points at the supply rather than at the oil. The hum test is the next thing to run.
The Motor Hums but Does Not Turn
If the motor hums but the platform does not move, the manufacturer lists two causes before anything hydraulic is in question: the motor may be single phasing, in which case the motor wiring and the line fuses are the ones that get checked, and separately the supply voltage may be too low, which the LS-Series page defines as outside plus or minus 10 percent of the rating measured at the motor terminals, a band wide enough that ordinary building voltage drift sits inside it while a genuinely starved motor cannot. A hum is not a dead motor. Power is reaching the machine. What is still open is whether all of it arrives at the right level, so the oil is not yet a suspect.
Both checks live on the power side of the table. Where the terminal voltage sits inside the 10 percent band, the supply is not the explanation and you stay with the wiring and line-fuse check. A reading outside the band puts the fault upstream of the table, where replacing the motor simply repeats the failure on a new one. The figure is written against the motor terminals rather than the wall socket, because the reading at the two points is not the same reading.
Motor Runs Fine, Platform Still Won't Rise
Once the motor is running normally, the listed causes move to the hydraulic side, and the first of them is oil level. The LS-Series page gives the level for two different platform positions, fully raised and fully down, and the two figures are not interchangeable, so a reading taken with the table down is compared against the figure for a table that is down. A reading taken in the wrong position makes the platform look either overfilled or starved when it is neither, which sends you after the wrong cause.
The other three items are quick to confirm. A table supplied with a solid plug still in the tank needs that plug out and the vent plug fitted, which the manufacturer lists as the fix for a plugged vent, and that is the one-minute item to do ahead of anything else in this branch. A clogged suction filter is cleaned as described in the periodic maintenance section of the manual, and a vacuum leak at the suction line means checking the fittings along that line.
The trade-off here is order rather than effort. Where the vent plug was never swapped in, go with the vent first, because a plugged tank vent explains a table that will not raise without any other fault being present. With the vent already correct, go with the filter and the suction-line fittings in that order, since both are suction-side restrictions and neither needs a hydraulic specialist to look at.
It Rises Partway, Then Stops
A table that lifts and then halts is a different symptom from one that never moves, and the LS-Series list treats it differently, because where the platform has reached its upper limit the upper limit switch may need to be adjusted. That is a stop condition rather than a power or oil fault, and it is the explanation to test first when the platform halts at the same height on every cycle.
The signal sits in the pattern. A consistent stopping height, cycle after cycle, points at the limit switch before anything on the hydraulic side gets opened. A stopping height that wanders, higher one time and lower the next, makes the switch an unlikely whole story and brings the hydraulic branch back into play. Consistency is the evidence, and it costs nothing to watch across two or three cycles before deciding.
When to Stop Checking and Call Service
The four manufacturer passages form a closed list, and that list has an end. Once the load is at or below the rating, the disconnect and the fuses are intact with the designated 20 amp breaker on a 110V supply, the terminal voltage is inside 10 percent of the rating, the oil sits at the level matching the platform's position, the vent plug is fitted and the suction filter is clean, the listed checks are exhausted. Whatever remains sits outside what this page covers, and no further guessing turns it into an in-house job.
Imagine a table that passes every one of those checks and still will not raise. That is the point where the trade flips, because guessing at a pump or a cylinder costs more downtime than a service call, and the part that gets swapped is often not the part at fault.
Before anyone authorizes a motor replacement, confirm the supply voltage at the motor terminals against the rating, inside that 10 percent band. It is the check that earns its place because low supply voltage makes a healthy motor behave exactly like a failed one, and a replacement bought in that state simply reproduces the original symptom on new hardware.
