So, I am unsure if the issue is the same as I had, but ill throw what i did into the mix.
About a year and a half ago, I noticed my crank bolt was hand tight, i tightened it, and the crank was wobbley as fuck (impact didn't have enough air flow last time i put the bolt on), so I pulled the dampener off and noticed my keyway was warn, and the key its self was fucked up and beat up pretty good. I ended up tossing a spare key I had laying around into the crank, mixed up some jb weld, dabbed it tight into the keyway in the crank with the key in place (the one side of the keyway in the crank was perfect still so I used that as reference), and put a new dampener back on(wasn't sure if the old dampener was still usable, and it slid on/off by hand so it was junk anyways) with anti-seize. I have removed the dampener and the keyway was still in the same exact spot, and is just how i put it in there from last time. I also haven't had any issues getting the dampener on or off since.
Hope that helps, if not maybe itll help someone. Also I did this on my original engine, that I have been trying to blow up for a few years, so I wasn't worried if it worked or not, but got lucky and it worked great! Still using the jb weld fix till it pops!
