Thanks Arctic, yeah I've overfilled it when I did the thermostat mod then......
I've ordered the Vitron seals anyway though as I thought the cap should never be that tight, my knuckles crack when I'm opening it which is never a good sign!
T-Cut, I tried the VIN display today, the last 5 digits matched my VIN plate so fingers crossed it's just a dodgy key but I'll do as you recommended and start a thread as it might save me a 70 mile round trip.
As an aside, I don't seem to be able to select option 7, it just resets back to the odometer. Also, I had an option 1.7 which isn't listed on your link?
Are there different levels of cluster?