Landing gear problem

[Snowbirds]

When I was raising my Monty off the hitch the landing gear stopped raising. I pulled the top off the leg and the motor would work but was not turning the gear in the leg. When the motor was working it sounded like something was slipping (clunking) in it but not turning the shaft. Are there shear pins on the motor side?? Any other suggestions...I couldn't see the screw shaft but there was grease on the gears...Do you think I should pour some oil down the legs? Many thanks.