The rear wiper is not really working, and I'm wondering if there's a fix or if I need to buy a new wiper motor. If the latter, is there a good link to an installation video that anyone might be able to share?

The wiring is OK, the washer fluid works, as does the remote lock.

Thanks!

It is probably salt on the shaft that goes through the hatch, the corrosion builds up over the years and makes it too tough to turn.

There are videos to show how to open up the rear hatch. Be careful removing the motor, take a before picture so you know how to position the linkages during install.

First, try some penetrating oil on the shaft. You may have to lift some of the rubber. Hold a cloth under the spray area to catch the overflow. Then turn the wiper on and help it turn by hand. Do this until it seems to go by itself, then use the wiper as much as possible.
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Keeping it running is better than buying new

Thanks Klaus! I'll give it a try.