I am trying to get an old Clark runnibg. It has been standing for 3 years. One drive wheel is totally locked, other is fine. I rebuilt the mastercylinder and bled the system. It released the stuck wheel a little but it was still draging. I pressed hard on the brake pedal, felt a click and the wheel locked up again. I opened brake bleeders to check operation of mastercylinder and it felt fine. One wheel turns freely, the other aboy 1/8" Help please!