[drolston]

Shade tree approach:

Line the stripped hole with a tube of tinfoil and put the original bolt in just tight enough that the lock washer is copressed so it will not come loose. The balance is preserved and the pressure plate could care less that it is fastened with five and a half bolts instead of six.

Alternatively, fill the hole with JB Weld, drill it, tap it, and torque it to about half recommended value.