Patricia (and TN98) 10 years ago I sold my LPL 7451 diffusion modular enlarger, however I photocopied the instruction manual.
I've just read through the rather basic manual, there is not really anything in it as to how one adjusts the fine points of lens/negative carriers.
There is one very important piece of information though:-
"ATTENTION! head/carriage and column are custom-aligned. Make sure they have the same serial number".
I think they are saying that the units are aligned quite precisely at the factory and if alignment gets out of whack, as in when the unit gets dropped, stiff.
Patricia, I could make a copy of this and post it to you, after all you're only a couple of hundred kilometres away.
I also made a copy of the wall mount brackets manual, for the 7450 enlarger. As this consists of one A4 page it is also not comprehensive, but the pictures make it interesting.
I had the wall mount and used it for the LPL 7700 enlarger before I moved up to the 7451 and kept the mount system for the the bigger enlarger.
I would say the wall mount brackets are brilliant, one does require a steady wall though.
Mick.