My son bought a Millers Falls 9C plane at a flea market and we have been refurbishing it. The problem we are having is when we disassembled the plane, the threaded rod that the blade adjustment knob turns on, unscrewed from the frog when we were trying to remove the knurled blade adjustment knob. There is no slot on the threaded rod to tighten it, so I am just able to tighten it with my fingers. When I do that, the threaded rod unscrews if you try to lower the blade with the blade adjustment knob. The threaded rod is reverse threaded so it tightens counterclockwise and loosens clockwise. So when I turn the blade adjustment knob clockwise to lower the blade the threaded rod unscrews instead of the blade adjustment knob turning on the threaded rod. Is the fix as simple as putting some thread lock on the threaded rod before screwing it into the frog? If that is the fix, how clean and free of oil does the screw hole need to be for the thread lock to work well? I can't think of another way to stop the threaded rod from unscrewing when I turn the blade adjustment knob clockwise.