Not that difficult, all screws on the back cover to be removed, then the lower board, after that the upper board to have acces to the tape unit which is fitted with 4 tiny screws. Probably Martin Dillen can supply the belts. I think he is reading all threads with the word "belts?
B&O item 1, B&O item 2, B&O item 3,...................B&O item 735
Beovirus? What's that?