The first thing you must do is remove the entire clutch assy, not hard at all, and look at the bearing lock collar. IF it is rounded off you must replace just the collar an add shims to obtain origional setting. You can have a hundred springs but if the back has moved away there will be no ability to prevent clutch slippage. The way to increase torque is to shim from the rear, not on the springs. The field was to set the shimms is to add shims with the springs left out until it locks and will not slip. Then remove a shim at a time until it will. Then reinstall with three, six or 8 springs.