Recently I found a Beocenter 3500 on the attic of my gran. Luckely it still works, but i'm concerned about the TT (the main reason why I wanted it :) ). The TT-belt has been off for a while (for some reason it was jammed underneath the center rotor (on which the record turns)). When i try to put it on, it slips down by itself when i turn the rotor (maybe it's has slackend??), it doesn't fall down when i don't move the rotor. Although I haven't tried it with a record on it, it won't turn automaticaly when I push the lift button (or so I guess). When I turn it by hand everything works: the arm moves in, lowers and at the end of the record it returns to it's original position. 

Can anybody help me? How can I make it work?

Greetings

It's very common to see the belt falling off if the transport safety screws are
tightened. Worth checking.

The weight of the platter also plays a role so in some cases, the belt
will also slip off if the turntable is run without the platter.

Martin

The transport safety screws are the screws on top of the turntable (without the platter on it?).

I still will have the problem with the lift button (or is that fixed too by loosening the screws?).

Yes, those are the transport screws.

The platter should rotate when you press the lift button. The deck does not sense
the presence of a record or the tightening of the transport screws.
If the platter does not spin, check if the motor spins.

Martin

So the tightening screws could be the issue regarding the lift button too? Or are these problems completely non coherent? (Sorry if I don't get it all, I'm quite new to the TT world).

Greetings