Have a look on ebay for a cheap working donor recorder as spares are very expensive and very hard to get hold of.
i'm guessing your recorder either doesn't read discs, or it won't eject? which is very common and means either the servo board is faulty or the laser.

The following recorders i know off hand for a donor mechanism are:

MARANTZ DR-6050
PHILIPS CDR-775
PHILIPS CDR-770

if it proves to be just a faulty laser, all 3 of the above have the same laser unit.
if it proves to be a faulty servo board, all 3 have the same servo boards except if you fit one out of a philips model it will show 'PHILIPS CD RECORDER' on the display at power up but will still work nontheless.
obviously if a marantz is found it will show 'MARANTZ CD RECORDER' as normal.

hope this helps.