As it happens, I did this a few months ago on my '98.
If it is spinning with no effect, you *can* take it apart and de-grease it. My passenger door motor was doing that. I took it apart, degreased the centrifugal clutch and it started working again. But I clearly didn't get enough of the grease out; it sometimes works, and sometimes doesn't. When you remove it, pay close attention to the three rods that connect to it and their orientation. And when you take it apart, be prepared to fight with a couple internal springs to get it back together right. Patience is your friend; it took me about ten tries before it went back together and worked right.
If you aren't that mechanically inclined, your best best it to get one from a boneyard. R&R isn't too difficult; reconnecting the rods will take the most time. They have the little plastic clip-over retainers that are common these days, so it's easy to disconnect; re-connection requires a bit of patience.
Caveat: the plastic case is 'welded' together; I had to break it apart. Because it was iffy, I used--no, not duck tape--electrical tape to hold it together. 3-4 months and it hasn't come apart yet.