405 DT rev counter and clock

[angry_mutant]

Have just bought a 95 (M) 405 diesel turbo. The rev counter stops working intermittently; it will run for a few miles, stop for a few miles, ru for a few miles etc etc etc!Every time I've been back to the seler it has, of course, been working perfectly. He muttered something about it being a sensor problem, but didn't really explain. Just wondering if this is a common problem, and if there's a simple way of sorting it.
The dashboard clock on the car works although the light behind it does not, thus rendereing it effectively useless. Is it possible to fix this light? And is there an easy way to ge the clock out of the dashboard - to the layman, getting to it looks to be a long and complicated job!
Thanks in advance.

[1900sr]

The rev counter is probably the multiplug on the senser cable. Open the bonnet, just in front of the injectors on the r/h side as you look at it you'll see a plug connector. Seperate it and spray with WD40, make and remake it a few times, this will hopefully cure it. (It cured my erratic tacho anyhow). You should be able to replace the bulb on your clock as well, though I understand removing the clock on a post 92 car is a bit involved (centre console, ashtray. stereo all removed [:(!]) Hope this helps.