I like the slide cube projectors despite their idiosyncrasies, mainly because the cubes are very space efficient and make it easy to shuffle slides. Here's a comparison of the slide cube and carousel projection schemes.
Others' experiences with projector maintenance:
Here are some places that will repair Slide Cube projectors:
Electrical schematic for a slide cube projector, along with some description of how the projector works.
Slide Cube parts - projectors, cubes, repair parts, manuals, etc.
As a result of this web page, I've gotten a pretty regular stream of mail about Slide Cube projectors. I have therefore started a Slide Cube mailing list, for discussion of anything involving Slide Cube projectors - operation/repair tips, offers of items for sale, requests for advice, information on availability of parts, cubes, and used projectors, etc. You can subscribe yourself to the list. This is a closed list; only mailing list members can post to it. The volume is quite low, as you can see from the archives.
Slide Cube Mailing List Archives