[Tucker Gunleather]

...........After I reassembled it, the thumb safety wil drop
when the trigger is pulled. I recall reading a fix for this but don't recall what it was.

Other than fitting a new thumb safety you may be able to place the current thumb safety in a vice and peen the metal with properly executed hammer blows. It will move some metal in the right direction to block the sear when re-inserted. Gotta' know where to peen though. I assume that you do.

If not, then take to FNG. I can't draw a picture of how to do this or find a picture that would demonstrate it.