Open it up and take a look at the big cam gear it must be blocked by something, the cam gear moves the arm, and is moved by the platter shaft gear.

Edit: Sorry I read RX2, do as Martin tells you

Push the tonearm carriage all the way to the right by hand and take off the record.
Lift off the platter and check the platter belt.

Martin

I have this exact same problem.  I am an original owner, and the TX2 has always worked flawlessly, but after an extended dormant period it jammed just as described during the automatic return at the end of an LP.  The start/stop gear mechanism is locked up in the middle of the return cycle such that the platter and the sliding chassis will not move in either direction (both belts are okay).  I can remove the start/stop cam lifting wheel and put everything back together the way it's supposed to be, and it will perform all operations correctly except for the automatic return at the end of an LP which will jam again at the same place.  This seems like such a specific problem that I was hoping someone would point to a particular broken spring or pin that would cause this symptom.  There is a cavity in the bottom of the cam lifting wheel that I think is for the pin on the record sensing arm, and the tracks in the grease suggest that maybe this pin is coming out of the cavity.  Is that possible?  Would that explain this jam?  How would you fix it?

Any suggestions (even just sympathy) would be appreciated.

Mine did the same.  You can remove the circlip and get the arm pulley moving again if you lift it slightly.  I'm guessing that the worm drive belt is slipping.  Anyone know what size belt it takes?

It's probably that well-known small arm under the rear cam wheel, that blocks the wheel when it gets distorted.

I can supply correct belts, both the platter belt and the triangular belt for the tracking motor.

Martin

Thank you! Yes I would like to buy the belts from you- please let me know next steps. Would like two sets.  Where can I read about the arm issue so I can fix?  Really appreciate the help

The arm issue was discussed here not a long time ago.

PM me for belts info.

Martin

I am a new owner of a TX2, and I have the same issue described here.  The platter just locks when I press stop while the motor continues to turn.

i know this thread is old but I looked for the small arm issue you mention above and find the discussion.  Can someone advise me on how to adjust this?  I took all the gears off, ensured they are properly lubricated.  I then reinstalled all gears attempting to ensure all are properly seated and engaged.  I still have the same issue.

im stumped

I meant to say, “can’t find the discussion”