Oil temp display

["Ian J Haseltine" <Jim_Haseltine@msn.com>]

The oil temp display on my Ur quattro has started mis-behaving.
All is well as the temp rises until the display reaches 1 segment below 130 
deg. then it goes dead. When it comes back to life it displays a lower temp, 
about 2 or 3 segments down. I've not tried taking the oil temp higher to see 
if the gauge works again at higher levels.

Any ideas? sender, control unit, wiring or gauge?
Are there any procedures for checking it?

TIA
Jim Haseltine
88 Ur quattro