[Fulltiming]

Not sure if it applies to the 1984's but the Bosch wipers on my 1992 have bushings that tend to rust with time and put enough tension on the wiper shaft that they tend to stall, especially at high speeds. Using a penetrating oil and using the wipers on a routine basis seem to help mine more than anything else I have done. Sitting for long periods of non-use, particularly in a damp climate are almost guaranteed to cause my wipers to hang from time to time. The other issue if the blade just hangs is to be sure the cap nut on the front of the shaft that holds the blade securely to the shaft is tight. A loose cap nut will result in the motor turning the shaft back and forth without moving the blade.