Sony WA-6000 walkman, cassette player not work

Hello all

So I’ve got a Sony wa6000 walkman, powers up radio works but not the cassette player opened it up to find one of the drive belts from the motor perished and the motor shaft was stuck managed to free it off tested it and it still works 
no power is getting to the motor only when I bridge it I have the service manual with basic knowledge 
where do i start to diagnose the problem with the multi meter which component is likely to be at fault.

2nd issue is only the left channel is working on the earphone socket can some one suggest how to diagnose they also?

I see a couple of these Walkmans have the same issue on eBay where the tape player doesn’t work. 

Any help would be much appreciated!