About the sticky carb piston, which doesn't necessarily have anything to do wit the car's not starting: you may have an off center needle that is sticking in the jet, which makes for an engine that can't be tuned. To correct: Screw up the adjuster nut, below the carb body, so the upper end of the jet reaches up level with the bridge. Loosen the lock nut (the upper) and press the piston down against the bridge. Also move it up and down a couple of times till it moves freely. Tighten the lock nut carefully and check the centering by lifting the piston 1/4 inch and letting it drop. It should hit the bridge with an audible click, like the other carb does. If this sounds like a lot of gobbledegook to you, buy, beg, or borrow a Haynes manual.
Good luck,
Bob