Hi Perry,
Sorry to not be able to give you an answer here, but I wonder if you managed to resolve your situation? I think I've had the exact same thing happen to me, moved into a new house and the boiler is missing a strip of white rubber-type material off the back of the front panel.
Gas engineer said it was an obsolete part and I'd need a whole new boiler.
Did you manage to resolve this?
Best
James, July 2012