Rear gear skipping
I'm a newbie hear and relative bike novice, though mechanically proficient. My problem is that my gear shifting has gone completely up the creek since i made some attempted adjustments. The original problem was some chatter coming from the rear deraileur and shifting to/from 5th smallest cog (i'm still learning the jargon) in the middle chain ring it would often not change properly at first and then suddenly snap in. At the time the bike wasn't exactly clean so i decided to clean it up and do a bit of maintenance. I basically reset the the H/L limit screws reset the cable in the clamp hoping it might fix it. I turned the the pedal crank while it was upside down (i was on my own and have no stand) and noticed some noise. I looked a little closer and it looked like the deraileur might be a little close to the rear cogs, so i adjusted the b limit screw as well. FYI i have a marin muirwoods (i've done a 1000 km) 24 speed shimano deore and alivo shifters . also i have to carry my bike up 3 flights of narrow stairs which causes frequent banging of my bike and i've had a low speed (over the handle bars) crash avoiding a dog so it's possible the bottom hanger might be slightly bent (i've checked but can't realy tell, so it can't be too bad.)
Anyway, the problem i've had coming into work today is that when rear shifting in the middle chain ring anything but the smallest 2 rear cogs cause the bike to not shift properly. I'll shift and it won't change or changes a long time after it should have or i'll shift again and it because it didn't shift properly in the previous attempt it shifts accross too gears. It also make a hell of a racket.
Does anyone know if this down to the limits (which looked right) the b limit screw, the cable tension or a bent hanger (or a combination) anyway if anyone could gibve me a clue that would be great