Got it – thanks Guy. I’ve got it out now – the thing I was missing is that you have to push down on two plastic lugs on the plastic cover, which you can then lift, tilt toward the back of the unit, and remove. Once that’s off, the tape deck comes out quite easily and I can turn it over and see where to get at the belts (or belt, in this case – Type 1 has just one belt it seems).
I’ll order the belts then (from Beoparts!), thanks, and replace the belts on both the BC8500 and BC9000.