Speedo and Tacho intermittent.

Hi all,
on my 97 300tdi, my tacho (or 'revcounter' to some) keeps dropping to zero while driving.
and then the other day, the speedo decided to read double it's correct value for a few miles ...then dropped to zero.
leaving it 'til next day they were fine again.
most of the time they work fine, but every now and again they play up.
any ideas? loose contact behind the panel? faulty senders/ECU?

hopefully this is a subject that has been raised before and someone knows a quick fix!

when my tacho and speedo did the same things as your desecribing, it turned out to be the alternator. Is the there oil over the back of it where the wiring is?

No, it's clean of oil.
However regarding the 2 wires on the back, one bolted and one push connector.
the push connector felt sloppy, so pulled it and reseated. seems to go loose when fully pushed on, so just eased it on and off till it held friction ...will have to give it a few days of trial to see if it fixed it ...if not i may be it's a dash cluster out as i suspect it could be a connector behind there?? (this is the usual problem when it happens with the Rx-7s - when the temperature keeps changing and expanding the metal, the connectors slowly 'walk' off the pins)