If the motor is turning and the belt is turning then the large pulley on the worm gear is loose. It is held onto the shaft by two set screws. You will have to remove the plastic housing to get to them. Don’t lose the screws.
Bottom part of the housing is held onto the top half by four screws set into holes in the top plastic housing half, these are small Phillips head screws. The top plastic housing half is held onto the mount by the four silver screws which take a hex wrench to unscrew. This allows removal of the clam shell. Note the db9 cannot be removed from the bottom half owing to the manner they installed it. So secure the clam shell with a strain relief to prevent damage to the motor wires.
I believe the removal process will be detailed in bob hoskins paper re hypertuning. It can be found in the files section of mounts or main subgroups on the forum.
Wes, Southport NC
EXos2-GT PMC-8, iExos 100
ES ED 127, 10" LX200GPS+wedge, Astro-Tech 8" Newt, ETX-90, 60mm no-name guide scope ~ 260mm FL
Polemaster, Orion ST-80 and SAG, ZWO 290MM, D5300 astro modified
Nina, Bootcamped Mac Mini control computer, RDP to iMAC
110 amp hour lead acid deep discharge battery for field power
Electrical Engineer, Retired