newbie derailleur question
I've got a Trek 930, it's been rock solid for probably 10 years. Starting to get chain slip, so I took it into a shop, and they told me the derailleur was bent so they bent it back the best they could (and told me it probably needed to be replaced soon). Wish they had told me that before I picked it up because I probably would have opted to just replace it, because after about 2 rides the problem is back.
So here's my question, I'd rather not pay retail pricing for a new derailleur (I'll still have them install it), but I'm clueless if there's any difference between them. All I know about my derailleur is that it's 1:1 actuation ratio and that it's direct mount (not a hanger). Are there different spur gear teeth or is that standard? (I would think different teeth count would affect the chain). I'd appreciate any response.