It's no good , I have admitted defeat on getting this superb vintage Aiwa CS-J1S  cassette player working !

When I acquired it last week at a local auction house, I was initially excited. When I put batteries in , it powered up , but the radio , or the player, would not work. I noticed the tuning band marker was not moving when the tuning wheel was turned. So I thought okay probably belts for the cassette and rope tension on the tuner. Upon investigating the belt change on YouTube, I was informed by a user that it was the hardest belt change he had ever done on a Walkman size player !! Well ,I downloaded the service book and duly stripped it down. Yes, you guessed , black sticky disintigrated belt residue. Also, the hook for the tuning spring on the pulley whee was snapped !! This I sorted by cutting a slot next to the broken segment gap , and I was able to reattach the spring !

When I started stripping the unit, the red antenna wire was found to have come off on the PCB !

I desoldered the other four wires which is required to allow the PCB to be folded out of the way, to enable access to the belt drive mechanism. Unfortunately the screws holding the assembly down were excessively tight, and I managed to damage the screw heads ! I then decided to drill the heads off and try to exteitbe tiny screws later. I finally managed to remove the assembly, and cleaned up the pulleys etc. , and managed to fit a new belt. I reassembled the drive mechanism , and soldered the plate back on , filling the counter screw holes , as I couldn't get the damaged screw threads out. I then attempted to resolder the wires . That was not too bad but the red wire came off at the antenna end !

My soldering iron melted

Any ways I decided to reassemble it without that wire to see if anything worked. Alas , when I fitted the batteries, nothing powered up. That's when I gave up ☹️.

So, this player is now Offered as spares or repair.

Basically:

Not powering up.

Some screws missing.

Some screws may be in the wrong hole ( different lengths).

The eject mechanism is not working correctly.

The perspex window on the lid has come partially adrift.

The wires removed for disasssemby may be soldered onto the wrong joint ( the service manual is quite unclear, though I did take photos)

The red antenna wire is missing ( fell under my bench ).

The plastic case looks damaged.

My soldering iron slightly melted a bit of plastic in  the square hole where the DC power in socket is located.

Any questions, then please ask. Gooduck !!

Dispatched with royal mail.