Electric landing gear not working

My QBBS (2009) has an issue with the landing gear, when extending the legs they start to take the weight off the truck (or ground) and then there is a thumping noise (coming from the motor/gearbox) and they do not extend any further. I can crank them down with the manual crank, so I think the bevel gears are good. The gear box seems to move around alot. I do not know if this is a clutch issue or a problem in the gear reduction box. How can I isolate the problem without taking the gearbox out/apart?

I also want to know what holds the camper up? If I have to remove the gear box and or motor will it come crashing down when i remove the motor/gearbox?

BTW the retraction works fine.... I first thought that there was pressure on the legs, because it was not chocked tight enough, but this happens on level ground, with no apparent pressure on the legs. I inspected the legs for unreasonable wear and they seem fine and like I said on retract they work flawlessly.

any help?
thanks in advance......

More than likely its the electric motor/gearbox. I changed one on our old 5er doing exactly what you described above.

The motor has gear reduction and clutches inside. It does all the work. It is the gear box and motor in one unit.

The only gears on the Cat are the final drive gears that transfer power from the horizontal shaft of the motor/gearbox to the verticle shaft of the landing gear. They are usually very heavy gears with little chance of them stripping. (The fact that you can hand crank them just fine, tells me the motor/gearbox is the problem. Sames as our old 5er.)

Our old 5er stayed in place just fine while I layed in the front storage compartment and changed the motor/gearbox. Its the gears (Can't think of the name of them to save my life) that transfer power horizontal to vertical that keeps the 5er upright. They can't move without the top gear being moved first. Its the same thing as the front jack on a travel trailer. Once its jacked in place it holds right there until the top gear (Hand crank) is moved.

Thanks, for the input, that is what I will investigate first.
I believe that Bevel gears are the type of gear that transfer the energy from the horizontal drive to the vertical drive.

thanks again, I will post what I find.