I have a Minn Kota Maxxum trolling motor that will not latch in the down position when I lower it manually. The only way I can get it to latch is press the go button which causes it to raise up quickly-then let off the button and it falls back hard and loud and will then latch. I have tried lubricating the pin and latch that has not helped. Could the spring be getting weak? Any help would be appreciated.