Generally either Printerworks or fixmyownprinter (something like that) has
all the info you need plus the parts etc. I even have a pretty good stash
of parts from some of the service depot auctions I have attended. I do tend
to packrat manuals too, so ask me and I will look, but mostly its the user
manuals.
I have a BUNCH of brand new memory expansion boards for a VARIETY of
different old laser printers (nothing very new). Brother, Olivetti, etc.
plus HP II, IId, etc. As soon as I get them organized they are going on
eBay. If you have an old printer you want a memory expansion board for ask
me NOW, as in many cases I have ONE only of certain odd printers. $10 and
shipping for a bare board (put your own old DRAM chips in it).