I have a friend with a 2003 410 Sundancer with 3126 CATs. His RPM gauges stick. With the boat off at the slip, he reads like 1,200 - 1,500 RPM. The starboard side used to be reliable and he would go by that and his sync gauge to match RPM, while the port gauge always read less. It's almost like they need to be oiled. Is this something that fails after about 13 years and needs full replacement or is it a connector problem?