Trolling motor question

[Edothedado]

I have an 18 foot G – 3 boat that has an 80 pound Minnkota trolling motor on it. I keep having problem with the bolts on the head breaking the plastic casing due to excessive bouncing of the trolling motor while in the store position. has anyone else had this problem and/or any suggestions on how to prevent this from happening again. I have repaired this five or six times and do not know at this point what else I can do to prevent this from happening again.