I have a 2000 150 h.p. Johnson with a new power trim unit installed about a year ago.Today I was out and when trimming up the trim motor would not shut down.I shut off the battery switch and eventually the issue stopped only to reoccur later on in the day.My question is what are the possible reasons for this problem? The trim buttons feel the same when depressed both at the motor and at the throttle.Thank you Andy