well it seems that i have a bad cell in that one side and now my question is how do i find it?

If you have a voltmeter, measure each cell. The low one(s) are most likely bad, especially if any are under ~0.9v.

Sometimes even if they're bad they may have a no load voltage that looks good, but as soon as you put a load on it (maybe even just a couple of amps) the voltage will drop right down while the good cells should hold fairly well.
If you test it with a load, it's best to charge the pack first other wise even the good cells may look bad.

Good point Patrick. I would load test each individual cell though...

the pack won't even charge past 600mah

Yeah, I meant each cell.