I have a NAP Quick Tune 1000 Pro arrow rest. The treads for the set screw for the spring tension knob have stripped out. Any suggestions on how to repair it short of replacing the rest?

If I'm thinking of the same screw, remove the knob and drill the hole out one drill size bigger. Then re-tap one screw size bigger and install a bigger screw.

If you tighten that screw tight enough to strip it out, you're WAY overdoing it. That screw just needs to be snugged down, not cranked down. You can either do what Phil suggests or order a replacement part.