Re: trim wont move up or down
hmmmm. the outdrive has position sensors in it that permit function at differen degrees of trim. have you tried pushing the up/out and in at the same time?
there is also a paired wirwe, that commonly looks like a lamp wire. two wires running together, that comes from the outdrive in the engine compartment, through the hull/transom, that controls those sensors. our mechanic says that these two wires often deteriorate, the insulation that is, and they ground/short out, causing a malfunction in that trim - up -down- in out switch.
your place to start with any issue in these switches is with a thourough cleaning of all contacts on the switch and pump. then check the wires discribed above. If that all checks out, use a circuit tester for current check. Then find out what style pump you have and go over the hydraulics to assure its all working proper.
A good laymen test is the two button test to move the drive up. that indicates the 'lamp wire' issue .
Those wires go into the drive, and complete replacment requires drive removal. For some reason, they seem to only loose insulation outside the drive in the engine compartment, so a new sectioon of wire is a quick fix.
the issue with the op's trim is not electrical, the pump runs but the drive does not move
the style of trim senders you refer to aren't used on an early 70's vintage boat, they werent invented til the late 70's
cutting and replacing portions of sender wires is a no-no, complete replacement of the sender is the only way to fix the broken wire(s)
to op:
the three button system you have is fairly simple to use, the bottom button, "in" moves the drive down
the middle button "up/out" move the drive up from the full down position to the top of the "trim" range - roughly 1/4 of the way to full up
the top button "up" work in conjunction with the middle button, i.e. you press both buttons simultaneously to move the drive up past the trim limit setting to achieve full up or trailer position
sounds like you have either little or no fluid in the reservior, an issue with o-rings/seals in the rams, an issue with valves in the pump, leaking fluid, etc...