I got some belts for a turntable and cassette player here a few years ago. https://www.turntableneedles.com/Drive-BELTS_c_2.html
I was just recording a tape for my car yesterday. It is an old Realistic double cassette deck with radio and turntable. The play only cassette died 15 years ago. The record side just barely works. I had to push start it from the back in record mode.
I odnt mean to advertise, theres a firm called bandridge I used to know the rep, they started selling belts & styli amongst other audio products, I see they are still going but theres no sign of rubber or styli on their website.
I've never jump started a cassette deck before!