conlog alarm cuts fuel pump power - common problem?

Hi

I was driving my Corsa, which while not exactly in its first flush of youth
('96) is generally still doing OK, to pick up a KFC when it simply
spluttered to a halt.

I then get to spend an hour with the Green Flag blokey pulling apart the
interior grunting about it being the fuel pump relay, until he decides to
tow me home.

Anyway, I figured I could do that myself - while I'm not too hot on motors,
electronics I can do. So I got out the (not-very-well-thumbed :) haynes
manual and figured out what was what.

Anyway, to cut a (very) long story (blimey those diagrams aren't exactly
simple!) short it turns out that the Conlog alarm is malfunctioning - the
fuel-pump immobiliser is cutting in.

Now I can disable the system altogether (manual key override), which lets me
drive around to my heart's content, but I'm not exactly happy with that
solution because I either have to lift the bonnet and re-enable it every
time I park or live without an alarm.

Of course I can also get around it by wiring around the appropriate
connectors but I was wondering if this is something which has a generally
known fix.

I assume since when I switch off the alarm the fuel-pump works that the
external wiring is functioning correctly and that it's a problem with the
internals of the unit.

I could of course get it professionally repaired but given that I won't be
keeping the car much more than a few months I don't want to spend any more
than I have to.

Any suggestions appreciated

Cheers

Geoff