I'm not afraid of doing fairly simple "drop in" work on a gun (changing stocks, adding new firing pin, springs, etc.). But when I haven't done certain work on a gun, especially if I have never owned or even disassembled one of those guns, I would like someone who knows what he is doing to at least hold my hand during the process.
Call me crazy, but when I pull the trigger, I want to know what is going to happen.
I don't see it as a sign of weakness to admit what I DON'T know.
Especially if it's something that could potentially be dangerous if done incorrectly.