Merry Xmas!
Looking at the manual schematics under Auxiliary Equipment, the governor relay and interval timer is built into the switch. Under troubleshooting it could be that, the motor or wiring. Check the ground by the motor and the connector real good. The Bl/Bk wire has to do with park. Since you changed motors you probably moved wires around where it made contact for a month. Pull the ground strap off and sand it well. Use dielectric grease on the connectors to keep moisture out.
When I first bought my car I had all kinds of weird problems. One is the wipers would quit when it rained. So would my headlight motors. The time you need them most, lol.
These cars are bad about corroded ground straps and moisture getting in the connectors. Buy a tube of dielectric grease by the silicone at the parts store. Take the time and clean all your grounds under the hood and grease all connections. It makes a huge difference. Things work : )
