guys i have an 88 evinrude 70 hp. trim is not always working in the up mode,(down is fine and control on motor works fine.up an down. how do i access the switch to check for loose wire.it is a white control box,with the lever type lift to start.do i need to remove the throttle from box to get to the 2 small screws i see so i can take off the plastic cover over wires going to the switch? i need help,thank you very much. rbass57