Nice tip Sam. I do the same with a needle file.
CC your thumb safety is just fit tight and thats exactly how you want it. Take the safety out and remove the grip safety and reassemble it without the grip safety. this way you will be able to see where the thumb safety engages the sear. you want contact and it will break in over time. Do not clip your plunger spring, not only will it decrease the tension on the thumb safety but it will also reduce the tension on the slide stop and you will start getting mid magazine hold opens. Just clean it, lube it and shoot the hell out of it..
Take it from a guy thats turned more than one perfectly good 1911 thumb safety into a trigger pull decocker..
Its all part of the learning curve.. Gunsmithing is a trade that has to be learned with the hands just as well as the mind..