I have a 27 yr old 1590. I would n't shut off. Went to that board, pryed plastic cover off of the relay and found the relay contacts had fused together. I cleaned off the contacts with fine sandpaper and it is now functional again.
The board they sell here seems ok but the mountong screw hole must be drilled because the board is longer. No big deal.
Feel free to email me if you have any questions.