I can't find the issue with my WM-EX50
I have a Sony WM-EX50 I wanted to repair. After repairing two other Walkmans by replacing the belts i was pretty confident, but after replacing the belt at this one, the player still doesn't really work. the motor spins, but mostly pretty slow and also inconsistent. sometimes it spins in a decent speed, sometimes not at all. I first tried a few different belts and since none of them worked I ordered a replacement belt for the exact serial number from the service manual but it is still the same.
things I think could be the issue but don't know how to test:
- Lubrication. I heard the right lubrication is important, since most oils etc. can damage the plastic, but I don't know which exactly.
- Motor issue. when there is no belt attached, the motor works fine, but maybe there is a bearing loose or smth. that only gets noticable when under work?
- belt too thick. the belt has a thickness of 1 mm. I heard that there are some belts with 0.7 mm thickness, but I couldn't find any reliable sources to buy them and since I bought a belt for the specific serial number I hoped it would have the right dimensions.
- belt routing. since the old belt turned into goo I couldn't check how the belt lay in the pulleys. I put it in the only way I found reasonable, but maybe I'm missing something important.
Any help or advice how to proceed would be appreciated.