tripmeter/odometer failure

[Jerry & Jane <janejerr@bconnex.net>]

Hi!
New owner of a '93 90 Sport Q, v6, and am I ever glad I found this site!
Yes, have read some of the Archives and have seen mention of my problem 
but not a solution.(Might have missed it.)
I have an electronically signaled, dial-type odo/trip (not LCD read-out) 
that is intermittent. It will work for 1/10 km to several hundred km at a 
time before quittinq. Sometimes, it will restart if the trip reset is 
pushed. Occasionally, it will start at random. Have dissassembled the 
speedo head as far as I can, but the dial pointer appears to be molded to 
the shaft (looked at it with a magnifier). It worked steady for a week 
after dissassembly. 
Is this a problem with the electronics, gears or the sending unit? Where 
is the sending unit? Is there a fix without going to a dealer?
Remember a post from someone who tightened the slack on one of the gears 
with a wooden spacer but wasn't sure if that was a cable driven or 
electronic unit.
Apologies if this has been answered before, but at 3 am I couldn't slog 
through more archives.