Regarding replacing the transistor, I just did one last night. I don't do much board work, but like to DIY when I can. Some advice based on my experience...

Make sure your soldering tips are free of oxidation (flux helps here)

Don't force things when removing the old transistor. I used a Hakko 808 desolderer and still had trouble with one leg. It's very tempting to start wiggling and pulling. That's a great way to lift a pad. I added more solder to the leg to build it up. Tried the 808 again and this time sucked up all of the solder. Transistor pulled right out.

I inserted the new transistor and bent the legs in opposite directions to hold it in place. Applied flux and soldered it in, then clipped the excess legs. It was the easiest part of the job. Cleaned up the flux with alcohol (get it all) and checked for solder splash and shorts. Lightly rubbed around the solder points with a fiberglass pen to clean those up.