Here's another contestant on the "Is the Channel Master 9521 rotator a dud".
I installed my first rotator in early/mid december. Temps were above zero and we had some rain. It worked great until the temps went back under zero. It seemed to work fine during the day and would seem to get stiff at night, moving at less than half it's normal speed, and would go out of sync because of this. Thinking it was my cable, I braved the cold and replaced my cable with a 5 strand 18 gauge cable. Of course, it was nice and sunny that day and it worked a treat. The next morning I tried it before going to work and it was back to its useless self again. I took it back under warranty, much to the surprise of the dealer ("we never have returns on these").
Luckily, we had a warm January and I got a window of time where I was able to climb onto my roof without killing myself. It worked perfectly and continued to do so until it rained last week. So now once again, I've got a useless rotator on my roof. My guess is that moisture gets in them and freezes.
So, bottom line is that these rotators are only good if you live in a warm climate. Maybe we'll all have to install small heaters in them to keep them warm and dry
I am so thoroughly unimpressed by Channel Master right now that I'm going to stop here before I say something about them that will get me banned from this forum.