I have a 2000 JCM 2000 DSL.  I've read much about bias drift being a problem on some of the early ones due to a defective PCB main board.  Are the replacement boards available commercially free of this defect?  Is there a specific issue of board to get in order to be free of the problem?  I don't have the issue presently on my amp but am considering buying a board to have as a backup.

Thanks!

Dave