HP-97 repair questions (a lot of)

[x34]

Got a giant lot of HP-97 and paraphernalia on local auction, including boxes, bag, papers, program listings (one with author's autograph, sic!), HPCC membership card, sealed original HP paper 6-pack, original and working (rebuilt) battery packs, etc. Lucky me!

But, easily predictable for 1979 item, there are two problems:

1. mag card reader, which I know how to repair.
2. printer does not advance paper properly - guess, feed mechanism should be fixed.

So, please, help me with fixing printer. The feed mechanism advances paper a bit,
one side better than other. Does it have two rubber rings on single shaft to do it?
May be, replacing the rubbers would fix it?

I could not find any photos and detailed info on fixing printer's paper feed mechanism. If you where to find such info and photos, please help me.

What are the differences with PICK version and motherboard revisions? How can I tell motherboard version and PICK chipset?

HPMUSEUM says Topcat series has opto-electrical keyboard, am I correct? Any details?

Seeking more info on NNNs, graphical/character printing hacks.

TIA, x34


I'm VERY interested in this marvel.