I wanted to leave positive feedback for Martin at Beoparts!
he has the *correct* triangular profile motor belt for the Beogram 5500 turntable.
I had bought one off ebay initially, that they said was the correct part. But it wasn't, it was just a standard round rubber belt. The 5500 turntable belt was designed with a triangular profile, to fit into the grooves of the motor and pulley
I would not have known this, if it wasn't mentioned on this great Beoworld forum. I came here for some disassembly instructions. Wish I had come here to research the belt, before I wasted my money on the wrong part!
ps international shipping can take up to 2 months ( I am in Canada ) so be patient
hope this is helpful to someone else