Tongue jack issue

If it starts working after raising or lowering manualy, the motor has a bad winding in it. When powered to operate, it skips over the bad winding. When you stop it, it stops on the bad winding and won't re-start until the motor is rotated past it.

If you have no separate ground wire, first thing I would try is tighten up the 3 bolts that hold the jack to the A-frame. They have a serrated washer that bites into the metal and if loose and/or corroded may not make a good connection. Happened to us on our almost new TT and that's all it took to fix intermittent operation. The foot pad on a tongue jack can move back/forth a lot and cause the bolts to loosen.

Two or three possible issues:
Dead spot on motor. Had this with my Steps on this Class A.. now on your jacks, this is not as easily fixed so I won't describe how I fixed it.

Bad switch. Sometimes the switch works one way only (**Suspect #1**)

Bad relay, if that is relays are used (#2)

To test the switch...
Switch will have either 3 or 4 terminals. if the wires are very heavy duty (like 10 or 12 ga) it will likely have 4 terminals Power, Ground Motor 1and motor two, Identify the MOTOR leads using a volt meter and using clip on test leads or jumpers connect the meter to it.

Operate teh switch, if you see Positive battery voltage one way, and negative the other the switch is working,,, IF you see boltage (Battery) when the motor does not extend.. (or Retract) the switch is not the problem.

If the switch has 3 wires.

Battery (hot all the time) UP and Down.
Use the meter to confirm which wire is the problem direction (will only have voltage when you command jack to go in that direction) Now leave it hooked up.

if the motor does NOT operate.. Does the meter show full voltage or something much lower Full means it's not the switch, Lower it is

Relays need to be located to test, but the test is fairly simple

Hook meter to motor leads as in the 4 wire switch test. Same test.

Is it a Barker? If so, it is the switch. Barker will send you one for free it is a common issue. They accidently sent me two so I now have a spare.

Now is the point in time where you gain a personal knowledge of the fuse, wires, switches and motor of your tongue jack.

You get to start by removing the fuse and reinserting it.

Check the tightness of the screws from the fuse to the motor.

Check the cleanness of the wire lugs and switch terminals.

Check the switch for an odd feel when actuated.

Check the gears(if any) and lubrication.

When everything checks out okay is when you find out why some of us are bald, some to white hair and some to whipped out the plastic so often it melts.

Sometimes the problem will manifest itself and stops forever but more often you will end up checking everything over and over until you find the problem.

Changing out suspected bad parts is sometimes the easiest procedure but it can be very, very expensive. Mechanical switches are a weak link fortunately they are usually inexpensive and if you can't find the problem, it may be worthwhile to change it out. Motors are most often the next weakest link. And ask anyone who has purchased a motor
from a dealer to replace a Ford window lift motor used in a Kwikee step.

All you can do is persevere.

Off the top it sounds like a loose wire that makes contact sometimes and other times not. I'd have to get into the wiring to confirm.