It was fitted from new, so around 10 years!
Spoke to Bazil, reckons it just needs the main unit replacing. Gonna cost me £200 as rest of wiring and installation is in place and should be good.
Will be an expensive month. Puncture in back tyre earlier this week, MOT and major service due next week and now £200 for alarm.
And I'm still waiting for insurance claim due to knob taking me out and causing me to drop the bike, may well cat-d the bike.
In which case, I'm beginning to think stuff getting the alarm replaced, bin it and do without. It only saves me £25 a year on on insurance.