Rock blues are awesome, get all the tar off. then sand the pads just slightly and what ive done before is cut little knotches in the opposite direction to the grind in my pads, worked really well. If there still getting stuck there either not set up properly/ near enough to the rim or maybe contaminated bits. p.s you can get the tar off by giving it a new grind or just biding your time and sanding/ cutting lumps off.