[Bigtel]

I managed to get hold of a like for like alarm unit off ebay and replaced the whole thing.
The relays are little circuit board ones so it should be possible to solder in replacements although a bit fiddly, to be honest I reckon a dodgy intermittent fuel immobiliser could cause big trouble if it caused it to run lean!
I was thinking of soldering more meaty relays in using cables to the circuit board and just mounting them near the alarm unit.