Scantronic 9450 - Can I obtain a replacement Outside Box?

Scantronic 9450 Alarm

Intermittent fault. The alarm occasionally sounds when not set. I am almost certain the fault is the micro-switch on the outside box. It occurs in heavy rain and I when I remove the cover it does not immediately turn off the alarm. The micro-switch is certainly dodgy.

Can the outside box be replaced and also I cannot find a replacement for the 9 volt battery in the outside box.

Many thanks