Trip Odometer Reset Inop

[Douglas Morris <dcmdcm@earthlink.net>]

My TRIP ODOMETER RESET KNOB spins, but the display doesn't change (yeah, I'm
pushin' on it, too). I don't want to yank the speedo unless there's some
likelihood of a simple (read: cheap) fix. Otherwise, I'll live with it
(geeze, I'm not *that* anal).

Questions: 
- Is this more likely to be a cable failure or an internal speedo failure?
(I'm guessin' internal, since the catalogs don't list a replacement cable.)
- Can anything be done, here, without yankin' the dadburned speedo?

DougM
74 CF18310OU