NAD 7175 PE vs. Newer Integrated Amps

In that case, there's also a "dry" version of WD-40 that loosens without the residual wetness as well as dedicated electrical contact cleaners. Either way, it's worth a try.

All the best,
Nonoise

Personally, I wouldn’t use WD40 to clean the volume control. I would use an electrical contact cleaner.  WD40 is good for rusty bolts and things of that nature.  When I worked in a Hi Fi and TV store in the 70’s and 80’s,  One of our new techs, fresh out of school, used WD40 to clean a TV Tuner because it was very staticy between the stations(the old mechanical type). The tuner was toast after that because it left a film on the parts and wouldn’t make good electrical contact. 

I've been using something called: "Super-Contact Cleaner." 
It gets the crackle out but I'm not sure it solves the problem of the occasional distortion...especially when the volume control sits for a while in the same spot.

Thanks for your suggestion!

Marc

It just occurred to me that it may not be necessary to open up your NAD to clean out the volume switch. Just removing the knob by gently pulling it straight off should give you enough room to spray some WD-40 from outside the unit. 

It's most likely that that is where the dirt and dust would have entered, if that is your problem.

All the best,
Nonoise

WD-40 is your friend. Your volume knob acts like a variable resistor or rheostat and is referred to as a wiper. It sounds like it's just dirty. Open the unit up and be careful as you use some compressed air to clean out the chassis as best you can. 

Short and soft blasts should be enough. Then, after you let it air dry a bit (some minor condensation will occur), direct the WD-40 with the straw as best you can at the backside of the volume knob and gently spray a small amount, and then give your knob a few turns back and forth. 

If you can, give it a listen before closing it back up as it may take another dose or two. In the neighborhood I grew up in, there was a neighbor who repaired TV sets for a living and his son told me that half the time, all that was needed was to take off the knobs and clean them out with WD-40 and his father would charge them for something else.

As for whether a newer integrated would sound better, I'd say yes. 30 years is a long time for things to age.

All the best,
Nonoise