broken speedo on 68 B

[The Warped Goat <dedwards@magnus.acs.ohio-state.edu>]

I took my B on a 150 mile run to    day and after 120 miles the speedometer, 
which had been reading a steady 70 mph, droppped to zero and stayed there.  It 
didn't work for the rest of the trip.  I'm guessing it's not a fuse since the 
other gauges work fine still.  Are there any tests I can carry out to find out 
what the problem is?  How can I tell if it is the calbe, the gauge itslef, or 
the sending unit?  Thanks very much.

Benjy.

-- 
                              
benj@proxima.cc.colorado.edu                 1968 MGB MkII      
b_edwards@rikki.cc.colorado.edu              1992 Trek 2300 Dura-Ace STI
bedwards@goedel.cc.colorado.edu              1992 Rocky Mountain Hammer