This might not seem important to the more-experienced in this group, but I thought I'd share it.
About two months ago I pulled out some Lux components I hadn't used in 15 years and put them in my bedroom as a second system.
The tuner didn't sound very good -- there was what appeared to be multipath on every station. I tried moving the antenna around, but it didn't do much good. This seemed odd, because I'd never had multipath problems with this tuner, and I live on the second floor of a wood-frame building -- not much metal or large reflecting surfaces in the neighborhood.
This morning the sound was really bad on the left channel -- down a bit, and very distorted. Moving the cables around indicated that the problem was definitely with the tuner, and likely somewhere at or following the multiplex decoder. I did not look forward to servicing the tuner.
Following my rule of "try anything", I turned the level control on the back of the tuner -- and that did it. The sound cleaned up completely including the earlier "mild" distortion I'd mistaken for multipath.
I've heard plenty of dirty pots in my service experience, but I've never come across one that was audibly distorted. A first for everything, I guess.