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.
