This track is a lot older than the tracks most folks would fix up, and the storage turned out to have been much more destructive than anybody thought, but there's a few things I learned that I think I should pass along.
First, it takes a close inspection to determine of the slot has altered. I saw sharp edges and thought everything was okay, and I was very wrong. The MDF had swelled enough to make the slot tight, and I didn't see it until a Carrera car with a big keel guide got stuck, wedged in a little kink. The more I looked, the more I found that there were lots of places where I needed to recut the slot.
When the track was disassembled, the pieces of glued and screwed flat plywood that reinforced the joints tore off a lot of the underside of the MDF, making the track extremely fragile right at the joints where the stress is when reassembling. Look out. I was lucky.
The old painted surface had to be repainted, of course, but I wasn't prepared for how much oil had soaked in. I had to treat the whole roadway with acetone (Prep Sol would have been better) so the new paint would stick.
Peeling old copper tape should be easy, but it does leave a hardened residue behind. I should have left it alone, as the places where I could still see it under the new paint were a lot easier to retape because that ridge made a guide that was perfect.
If anyone gets into one of these situations, I'll always be glad to answer questions here.