have a straight shaft (fc85). blade bolt has become hard to screw on/off. Use to you could crack it loose and remove by hand, same going back in. Now, once started, you have to wrench in or out. Appears the threads have gotten boogered up. Tried a new bolt and same thing happened once it hit bottom. My question, would tapping the screw hole using same size correct my threads good enough to get a bite to hold bolt. fyi..It does not appear the old bolt was crossed threaded. Thanks for any input.