How repairable are Selectavision and other CED players

[Electronic M]

Most common problem on them are failed rubber belts... They work like a linear tracking turntable the stylus carriage advances with a rubber belt driving a gear train.
The early models with the big mechanical loading lever have fewer belts and less to go wrong but are fully manual load. The later models with push button loading are more complex but offer stereo sound in most models, and have the cool feature of pulling the caddy in then ejecting the empty caddy most of the way automatically.
Some of the later models have IR remote control and some can play interactive discs.
Another nice feature of the later players is using visual search to fix skips... You can't really clean the discs so if one skips you replay the part a few times until the dirt dislodges and flies off... I've had discs so bad you couldn't follow the dialogue go to like new in a couple of plays with a lot of back tracking on every Skip.