@AMIGAZ: just my 2 cents on this subject.
Dont sell the card! Its THE best gfx card for high end Amigas!
first, try all what was suggested. As last resort, i think sending the card to Amigacenter in France is worth every penny (Of course, if the reapir doesnt cost same as getting a used PIV). but my guess is, it will cost only a fraction to get it fixed!!
Good luck!!!
Sebastian