Hi I just rebuilt my bike, like new paint grease steat ect... Well I am trying to put my shimano acera front derailer back on and its just not working I have the cable off and have started messing with the screws plus I don't know were to mount the unit now that the bike is painted and i didn't mark were it came off. can someone help me it worked before so the chain is fine and i am sure nothing is bent.