Reading what you posted, sounds like the linkages may be the problem.
NOTE: I'm not familiar with the wiper system on a 51, so I am using my familiarity of a 59 wiper system.
1. Remove the wiper blades, run the wiper motor under engine power at idle.
2. If the wiper motor runs normal, the wiper blades/arms may be the culprit. Determine which, if not both, is the problem.
3. If the motor barely runs, remove the transmissions.
4. Check that each end where the wiper blade attaches (tower) pivots freely. If good, continue.
5. Check the pivot area inboard of the tower to be sure it pivots freely. If good, continue.
6. Check the end that attaches to the motor by either putting linkage on a rod the same diameter as the motor pin or connect it to the motor and rotate the transmission to make sure it's not binding there.
7. If any place on the linkage is binding, remove whatever is causing the bind or replace the bad transmission.
8. Reinstall linkages one at a time and check motor operation with engine running at idle.
9. When wiper motor works to your satisfaction, reinstall wiper blades one at a time and check operation with engine at idle on a WET windshield.
10. If no issue is found with the wiper blades/arms or transmissions, the issue is inside the motor.
Remember, ALWAYS operate the wipers on a WET windshield.
Last edited by Cablesmill; 05/26/2017 7:23 AM.
