What lock is it ? Possibly I have a photo I can post for you go by. Sounds like a L&R and the lil Link that connects the tumbler to the mainspring ? It is S shaped & on a RH lock it goes in looking like a S. On a LH lock it would look like a backwards S. On each end of the link you have the ? barrel I will call it, that latches to the mainspring & the other end to the tumbler. The thickest barrel goes on the Bottom. If you put the link in upside down or reversed, good chance you will break the tumbler or the link.