Jj2468, if treated with care, old tapes can have excellent fidelity even if made in the 1950s.
Ken, I use a sort of commercial timer oven for making pizzas, which works extremely well since it takes a while to warm up. I've also used my oven at home, and just block the door slightly so it can't close completely- I've had good results with that too.
It seems like it might be a bother, but you only have to treat a tape this way maybe every 5-6 years or so. I'm glad I didn't throw out the old tapes for my Mellotron :)