That early FEF was prone to failure. The appropriate way to repair this is with a PS-32 5V board that is installed in the engine as original. If you go the TMCC route you loose the full functionality of the integrated smoke and all those lights. Or you go with GRJ tach and super chuffer which greatly adds to the cost and labor.
I have done plenty of these engines if you want it repaired with PS-32; and my cost for this engine will be less than the TMCC parts to you. E-mail in profile. G