you could try contacting ColorBAT--I know they used to service 45As, and carry the manuals and some limited spare parts. The big problem with the 45A is that besler doesn't support it anymore.....
fwiw--ColorBAT used to put out a series of tech sheets for labs--the BAT part stands for "Beyond additive techniques" or something like that. The tech sheets dealt with just about every facet of labwork--but had alot of info on Beseler enlargers--the 45A in particular--and jobo processors. I have a set from '93-'97, and they only briefly mention b&w printing with the 45A (they give some approx grade settings), but they cover in depth how to use the probe/controller for sensitometry, how to calibrate the head for making internegs etc.
hope this helps