Thank you to Wingnut and others for the tremendous help. I did this job recently and shared some points below that others may find helpful. I’m handy, but not a mechanic, and the repair took me about 90 minutes. I did not use any new parts. Had I replaced the linkage assembly instead of spending time to free it up, I’m guessing I may have spent 30 minutes less on the project.
The problem:
I sensed something was wrong with the wipers when they seemed a bit slow. I passed it off as an aberration, but one month later was surprised when the wipers went half way up the windshield and stopped. I was able to move the wipers by hand to get them back into their rest position.
Some experiences with the repair:
The wipers appeared to be stuck on their shafts, and I do not have a puller small enough to fit around and under the wipers. Instead, I let penetrating oil soak in overnight, installed the nuts upside down (flange up) and backed them off a bit to protect the shaft, gently but firmly pried up on the wipers with a flat pry bar, and rapped the ends of the shafts with a hammer. Still, the wipers did not come off. Then, I lifted the wipers to the upright position and wiggled them up and down, and they came right off. I’m guessing everything I did loosened the wipers a bit, but the spring pressure of the wipers against the windshield may have prevented easy removal.
The driver-side shaft was seized. I applied penetrating oil and clamped the arm of the shaft into the vice (not the other way around.) This way, I had lots of leverage moving the whole assembly back and forth instead of trying to turn the shorter arm at the end of the shaft. It took five minutes of rotating the assembly back and forth along with some vertical pressure to remove the assembly from the shaft.
The bottom half of the shaft was corroded and pitted. I polished it with 80-grit paper until it moved freely in the bushings and reassembled with a high-quality synthetic grease.
I experienced difficulty replacing the snap ring on one of the shafts because the snap ring groove was partially blocked by the washer. Perhaps the washers were of different thicknesses and I hadn’t replaced them in the same spots. In any case, after finally getting the snap ring in place, the shaft did not rotate as freely, but it seemed acceptable.
The plastic tray at the bottom of the windshield would not snap down into position easily. Therefore, I applied silicone spray to the groove. Then I was able to use some fairly sharp blows with my hand to snap the tray’s locking channel into the groove - starting on one side and working my way to the other.