One of the brake calipers on my 940 is starting to get pretty sticky (one of the pads wore down all the way when the other was only half worn), and all 4 of them are dragging a little. I see that new calipers are only $40 or $50, is there any way rebuilding them (myself) makes any sense? The seal kits I see online are $30-$40. And if I do look at replacing them, is there a brand to look for?