Here is nice tutorial how to change supply (left) pinch roller:
http://www.tapeheads.net/showpost.php?p=405684&postcount=3
http://www.ant-audio.co.uk/Tape_Recording/Service/Rollers/album/index.html
Here are nice video tutorials how to change belts or pinch rollers:
SONY TC-K790ES
Nice video tutorial how to change new belts and pinch rollers for SONY TC-K790ES (language: German)
SONY TC-WE725
Nice video tutorial how to change new belts for SONY TC-WE725 (language: none)
SONY TC-WE805S
Nice video tutorial how to change new belts for SONY TC-WE805S (language: English)
SONY TC-WR545
Nice video tutorial how to change new belts for SONY TC-WR545 (language: English)
SONY TC-WR635S
Nice video tutorial how to change new belts for SONY TC-WR635S (language: English)
SONY TC-K750ES
Nice video tutorial how to change new belts and pinch rollers for SONY TC-K750ES (language: none)
SONY HST-H30
Nice video tutorial how to change new belts for SONY HST-30 mechanism(language: ?)
SONY TC-WR870
Nice video tutorial how to change new belts for SONY TC-WR870 (language: none)