Looks like a great deal, especially if there is a LM317 or some other voltage regulator involved as ThreeDogsNE said. I can't IMAGINE that is it just a plain old potentiometer mounted on a plate!
A good source for rare earth (neodymium) magnets is www.magnet4less.com
I use the ND021 button style magnets for the stir plates I build, they are 1/8" x 3/8"
www.magnet4less.com is also a good place for magnets, they have a large variety of shapes and sizes. I use the 1/8" x 3/8" button style magnets, 2 for each stir plate.
+1 to Accidic, it's important to get ones that are polarized axially. In my case, through the 1/8" dimension.
Fly,
You can use two button magnets or one single bar magnet, both will work OK.
Just make sure that your button mags are arranged with north pole up one side and north pole down on the other.
I think the reason your stir stood straight up is the fact that your drive magnet is...
Llysse,
Yes, you can remove the four cover screws and check to make sure the two drive magnets are still seated properly. They should look the photo on the "Do It Yourself" page of my website www.stirstarters.com
Stir bars usually don't go bad, so it's probably something inside the stir...
Hi,
If that's a StirStarter stir plate, and I believe it is, since Rebel Brewer in one of the online retailers that sells my gear, it's guaranteed! I will ship you another stir plate if you will PM with a shipping address.
I apologize for the inconvenience, I test every one before I ship...