Hello All,
First, let me thank you all for a very informative forum. I have been "trolling" through this forum since this spring when I bought a boat with twin 200 HPDI's.
The questions:

1) I am having trouble with the twin trim and tilt switch (the one on the throttle arm) on a 704 remote controlbox. It had been working off and on, but now completely failed (will not work in either up or down). The individual port and stb switches mounted on the box still work, however they don't work all the time. I have a copy of the wiring diagram. My thoughts and questions:
a) I don't think that it is the relays as both motors tilt on the individual switches.
b) Could it be the switch itself? They seldom fail in both directions. I suspect it may be the hot "red" hot lead. Str ange though, that the red lead is routed to the port engine. Anybody have a similar problem?
c) Could it be the harnesses to the engines?
2) I recently changed out my tachs. The port engine trim guage is not working. I swapped harnesses with the stb engine and the guage works fine. I will try to meter the leads as specified in Seloc. Is it unusual for the trim sender just to crap out?
Any thoughts would be appreciated.
Many thanks