Have you check if the arm move back ans forward when you start and stop. The arm with the white piece under the pin. When the arm move forward the pin go up. A little plastic pin drive the arm in the center wheel. Maybe is unset or broke.

I'm looking at the same issue myself. You have to lift the rod that connects it to the center mechanism at the center..

I don't think that removing that pin will help. It's just there to keep the plastic part from rising off. I believe that the brass pin also has limited motion by design, but using WD-40 or the like (penetrating lube) may help. As far as what's causing this, the tonearm has a cueing feature. Look for a part that is holding the tonearm up. That would be the part that's locked in the up position. If you are not averse to spending money, Soundsmith in Peekskill, NY can probably repair it. They are quite good.

I have the same problem. Couldn't remove the pin. It's moving though, after cleaning it and lubricating but it did't sove the problem with the tonearm movement... stuck in this project as well. Let me know if you find the way to do that. Have you tried beo forums?