When i use the B&O turntable, it occasionally speeds up. I've noticed that the longer it's in use, the more prone to the speed up.Is this something more than needing a new belt?
It probably needs some new speed setting trimmers. The problem is with 33 and 45? Or there are bad solder joints. Or the supply voltage (internally) is no longer stable. In any case it will need a set of new capacitors in every section.
Indeed,as above,but also it's worth checking the turntable motor.The bearings may well have dried out with age,so that as the unit warms up the bearing's free up and the turntable runs faster.
You can download a strobe disc from the 'net,so that you can monitor the speed at start up from cold etc.
Nick