welcome to rcu with your first post. I am not a cx2 guy, but I'll see what I can do.

do you have a way to check the voltage of the battery pack? that would be the first thing to check out. If that is good and checks out, there are a couple more things it could be. One is also double check the voltage of the cells in your TX, I don't remember what people were saying was a good votlage to be above, but something like 5.2v or so.

Also something like one of your shafts could be bent, or maybe you got the motor too tight or too loose on the main gear when you put it back together. Teflon lube is probably the best to put on these heli's if you're gona lube it up. Also your motors if the crash was too hard could be going down hill.

hopefully some cx2 guys with some more experience can fill in here =)