HI, that's going to be a tough problem to solve....
Its an old printer and most folks would probably say that practically anything that goes wrong with it is going to look like a
"beyond economic repair" situation.
It may be worth while consulting your local IBM support person, or printer repairer, and spending time on Freecycle and popula on line auction houses looking for either parts or complete machines that you could either use, or strip for parts.
Various firms advertise repair services and it may be worthwhile speaking to them, but you will probably have to spend a great deal of time, energy and resources to be able to locate working parts that you need.....
I fired up my favourite search engine and came up with this link that seems to operate in the US of A ( its not any form of recommendation but just identifies the sort of folks that say they may be able to help....) you will need to make your own enquiries and start creating a list of "potential sources".... then its a question of speaking/contacting them to see if they really can help...
Good luck with your quest.
Incidentally if you do find a suitable working part do you have the workshop facilities and know how to fit it?
It might be worthwhile considering these issues at an early stage