When you take the carb off, look for a gasket between the carb and the intake manifold. I think that its a common error to install a gasket that blocks the vacuum port on the base of the carb. This vacuum port is for the power piston and a stuck power piston may be your problem. Carb kits come with this gasket - just because the kit includes the gasket it doesn't mean it should be used.
I suppose that there are garages in your area that could rebuild your carb. You could hand them the carb and the kit and let them do it. If it takes them more than an hour (not including soaking time), they don't know any more than you do. Don't give it to the guys at the Lazy Boy Garage!
If you DIY, I think that the biggest confusion is keeping track of the (5, I think) springs. Take some pictures as you disassemble the carb. The instructions sheet and the video are not really helpful in pointing out which spring goes where. It's mainly common sense where the springs go, but I trust pictures more than common sense and memory.
