I put a want ad up for a new or used coil.new from fisher themselves is way out of my budget range.
I don't think a coil is going to fix your unit. Have your tried to locate someone close to you with detector???? So they can look at your unit and swap coil. It would I think be worth a 60 mile drive just to see rather than laying down dough for even a used coil. Or find someone willing to help you and you ship your coil to them to check it out for you. Shipping cost round trip would cost, but you may be further ahead in the long run.