To stir or not?

I made a stir plate. It was good but I'm
having trouble keeping the bar centered. I used earth magnets mounted on a washer it'll spin and be fine but inconsistent. As it jumps to side of jar and gives me a hell of a time getting back centered. I was planning on using my one gallon carboy to build my yeast. I don't know if I ca add a magnet to center of fan or if it would help. I'm sure there are people with way more knowledge and experience resolving this issue. Lots of threads but I didn't have time to search them all for resolutions. Cheers

I just built my own using a hard drive magnet. In reading i found some setups work better with 1or 2 inch bars. Try a diff size maybe.