Hi Peter,
The gauge will have to be replaced, cant put my hand on the manual at the minute to get you out the part number (if you have the installation manual there it will be in the back of it)
Ideal parts can be had from your nearest Heatmerchants (maybe not stock item, but the can get it for you)
I am Ireland based (Dublin/Meath/Louth) so if you need anything further and are in my area just mail me tony@oilburnerservices.com
btw....first Irish post I have seen here......!
T
June 2008