Reset Rev Counter

I have just bought a 2000 S1 and the Rev Counter starts at 6,000 revs, does anyone know please if it's possible to reset it to start at zero or is it going to be a new unit, (the previous owner said it did it when he re-fitted the battery after charging) sorry if this has been answered elsewhere but I had a look and couldn't find anything

When you switch on the ignition the Stack recalibrates needles to zero. This is the light juddering noise that the Stack makes as the needles are pushed against the end stops. If the Stack has any input while this is happening, it will recalibrate zero at that speed/revs. So if you happen to reset the ignition while the car is doing 30mph and 1500 RPM, these will be the new zero values. So at 30, the speedo says 60! A useful tip for getting spectacular 'how fast was I going' pics, but otherwise a pain.

Simply stopping and resetting the ignition a few times will eventually get the dials back at zero. A single recalibrate is often not enough, as it only seems to be able to reset about 10mph at a time.

I know this as one of my car's peculiar traits is that the Stack goes out of whack when it's subjected to fast changes in altitude. I noticed this first on a trip from North to South Wales through Snowdonia, and then last year on several alpine passes on the Stelvio trip. Some other S1s on that trip also had this problem.

I think this may be related to condensation, as it is often accompanied by a steamed up Stack glass. Once temperature/altitude is stable it all seems OK, once reset.

So it may be a case of QAFTDS (Quite A Few Do That Sir!)