I just bought a Schwinn Admiral with a 7-speed rear. I knew I'd have to make many adjustments because it came from Walmart. The specific issue I'm having is getting it to shift properly. At first it would click squarely into every gear except 1st. It would go into first if I twisted the shifter past 1 but it wouldn't stay there if I let go, so out come the tools. Unfortunately, everything I do seems to make it worse. The very first adjustment sent the derailleur into the wheel and bent a spoke. Subsequent adjustments made the shift to 1st better (and safer!) but it'll either skip gears, shift onto the axle past 7th, or only shift to 5th. As it stands now it's almost exactly the way I got it: shifts into every gear but 1st, except now 3rd is noisy. It's driving me absolutely up the wall that I can't get it right!

So should I take it to a professional or do I just need more patience? Mind you, I've made something like 15 adjustments already.