Update
First off, it appears NAPA rules when it come to everyday parts for vintage vehicles. NAPA was the only place that stocked and properly referenced the correct fan belt for the Jimmy, and I just replaced it this past week. The previous belt that was supposedly the correct one per a less with-it auto supply chain was 1" too short, had the wrong pitch, and really squealed at higher RPM. It was a PITA to remove.
Well, regarding the wiper motor, I sort of made some progress. I pulled the motor apart and cleaned it out again, gave it some silicone lubricant and closed it back up. I started the truck, held the motor in my hand and attached the vacuum line to it. I switched it on and the mechanism started moving, but just barely. I took the motor back to the bench and tried the revival method I found for a '33 Plymouth, which advised to attach a very short length of vacuum hose to the motor, cock the motor 3/4 to the right, dip the end of the hose into a small container of refrigeration oil (I used turbine oil) and then move the mechanism 3/4 of the way back, which would cause it to draw in the oil. I repeated this once in the opposite direction per the instructions, then went back to the truck to check for operation, and what a difference! The motor was running smoothly and at a decent clip. I put everything back together and ended up with the original issue. No return sweep. Barely even an initial sweep. I think now it's a case of the linkage needing attention, and a tighter fitting vacuum line.
I'll pull the motor again and run it without the linkage and see how it behaves. Then I'll know what to do next, and that may include sending it off for a rebuild.
First off, it appears NAPA rules when it come to everyday parts for vintage vehicles. NAPA was the only place that stocked and properly referenced the correct fan belt for the Jimmy, and I just replaced it this past week. The previous belt that was supposedly the correct one per a less with-it auto supply chain was 1" too short, had the wrong pitch, and really squealed at higher RPM. It was a PITA to remove.
Well, regarding the wiper motor, I sort of made some progress. I pulled the motor apart and cleaned it out again, gave it some silicone lubricant and closed it back up. I started the truck, held the motor in my hand and attached the vacuum line to it. I switched it on and the mechanism started moving, but just barely. I took the motor back to the bench and tried the revival method I found for a '33 Plymouth, which advised to attach a very short length of vacuum hose to the motor, cock the motor 3/4 to the right, dip the end of the hose into a small container of refrigeration oil (I used turbine oil) and then move the mechanism 3/4 of the way back, which would cause it to draw in the oil. I repeated this once in the opposite direction per the instructions, then went back to the truck to check for operation, and what a difference! The motor was running smoothly and at a decent clip. I put everything back together and ended up with the original issue. No return sweep. Barely even an initial sweep. I think now it's a case of the linkage needing attention, and a tighter fitting vacuum line.
I'll pull the motor again and run it without the linkage and see how it behaves. Then I'll know what to do next, and that may include sending it off for a rebuild.