When I mess up screw holes on locks, I usually pien a screw in the hole and re-drill. If I do a good job, I can't even find the repair again. You can't pien a screw in the tumbler hole, but you could braze/silver solder a screw in. That is what I would do, then re drill and tap. If I had the TIG welder I would like to have, I would fill all these holes with matching steel. Maybe one of these days. I have my eye on a Miller MaxStar 150. The whole outfit is $1500 at my local welding supply company. I know that is not a lot of money for a lot of you, but it is for me.