Re: power problem
The NT carburetor does not have an idle port, so the only thing to really clean out is the main jet and bowl. Sometimes trash can accumulate in the fuel control valve, commonly referred to as the needle. It's what the float in the bowl controls.
Taking the head off is nowhere near scary. It's 4 nuts. Once off, there's only an aluminum gasket to take off. That's it. Lapping the head is easy too. Get a mirror or a section of glass. Something very flat. Tape some 200 grit sandpaper to it. Get a magic marker and color the bottom of the head. Let the ink dry. Now lightly sand the head on the glass. Use small swirls. Do a few circles, then turn the head 90 degrees. Repeat. After a couple light passes, take a look at the magic marker. Are there spots it didn't sand? If yes, keep going. If no, the head is true.
Tip: you can even cut out your own head gasket from disposable turkey roasting pans.
(super secret tip: if the head and cylinder are 100% true, you can use a thin layer of copper rtv sealant as a head gasket. Ask me how long mine has been like that!)
Never stop wrenching