Those are obsolete and there are 2 or 3 different boards that fit them making finding the correct one a real challenge.
RainSoft dealers are instructed not to make major repairs on brass valves.
There is a possibility it could be fixed.
RS dealers are instructed to offer you a new composite valve or a brand new softener.
Either way it's going to be expensive.
You do have options outside of RainSoft...
HTH ~