Luxman 3045 mb

I have these wonderful Tim deParavincini designed amps from I believe the early 70's. Anyone out there have experience with upgrading, moding, servicing. I switched to KT 88 output tubes 10 years ago.
Thanks all. I do not have any technical experience with amps although I can and have replaced components. Can anyone explain to me how to find the items you mention: feedback loop resistors and capacitors; plate, grid, cathode, feedback resistors, and others. I have the circuit diagram with all labels and voltages, but I don't know which components are the above mentioned items. Many thanks again, I would love to keep these amps!
I believe you have a better chance of getting specific technical advice if you post on one of the tube DIY forums.
I had the factory KT88 conversion procedure manual mailed to me from Luxman. I can mail you a copy, email or snail mail. I converted my amps some fifteen (20?) years ago, and have been quite happy. The old design had the tubes right on the hairy edge of the operating envelope, that's why they went through output tubes and needed frequent bias adjustment. With KT88, you set the bias once (check after a few hours of break-in) then forget it. I have rechecked the bias after five years, and it remained rock solid. I have since upgraded the caps and resistors, and true to what Shussbliss says, I heard noticeable improvement.
Stevenm, having had six of these amps and having to bias them perhaps twice an evening, I wish I had known of the KT88 conversion. Did they sound as good as the original tubes? I had them on Fulton Premiers.
Fortunately, I acquired a pair of these last week. It has the KT88 mod above.
What preamps are you recommending please.