Vintage Luxman L-450 crackle and hum

Hello all, I have an update and a question after one year. I took my Luxman L-450 to Jude at Pro Audio Repair in Crown Heights as recommended, and he was great. The unit sounds terrific now and is everything I could hope for. Except for one recurring problem.

Every few days, the right channel will cut out. The left channel still sounds great, but the right channel is just gone. (Not dead silent, but almost.)

One clue as to what is happening is in how I get the right channel to start working again. I am running my source (an Auralic Altair) through the Aux input. If I flip to another input, then turn the volume WAY up, I can hear a little bit of noise bleeding into both channels. And if I then turn the volume back down and flip the selector back to Aux, I now have the right channel back. This works pretty consistently, but it is irritating!

It seems like there is some kind of power problem in the preamp stage, and blasting it resets things for a few days, but I don't really know if that even makes sense.

I took the unit back to Jude for a look, and he cleaned everything up and sat with it for a few weeks, trying to reproduce the problem, but he couldn't make it happen. We finally gave up. (No charge from Jude! He is really great by the way.)

What does this sound like? And how can I remedy it? I'd be grateful for thoughts!

Many of the problems on the Luxman units of that vintage were due to the thermal breakdown of integrated circuit modules (DML's) that are no longer available. There is a guy in, I believe, Holland named Hans Hilberink that makes replacement modules that are supposed to be better than the originals.

One of the best guys in the states for Luxman repairs is Tom Ishimoto at Northridge Audio in California, but Hans probably knows of someone closer to you. Hans posts on the Luxman Yahoo group, and is a goldmine of info.
http://www.hilberink.nl/codehans/luxman.htm

yes.

switches and knobs are noisy when disturbed which isn't issue of current discussion. noise that comes without disturbance of knobs and switches is coming from circuit components.

Switches will also be an issue. Lube-cleaning them is generally a short term solution.

As in we hope we get lucky but no one has ever managed to be in that 0.5% (or whatever it is) percentile of people who somehow have all clean non-oxidized switches after 30-40 years.

I take them apart and clean the contacts with 3000-4000 grit sandpaper, to remove the oxide build up, the kind that never really comes off with any 'treatment'.

It's a huge job, at best. Not worth it for the the average person, unless they want to keep the item.  No one would every pay for the work, it's labor, labor, labor to the max. $400-500-600 labor on a $300 integrated? Yes, very possible. This is very much a DIY thing, not for the faint hearted.

pro audio repair in Crown Heights

I feared as much! Is there a go-to guy in the NYC area?

there will be caps and some transistors to replace.
i have list of transistors from 70's that will tend to become noisy after certain hours.
there are lots of techies repair vintage electronics.