I have just noticed that the keyswitch is missing the plastic arm that pushes the Microswitch in, and that also allows the solenoid to lock the key switch
PJF, thanks for that.
By the way, I'm one of the 'old timers' been at it for 30yrs+, ask your guys if any remember the Model 88, 89 or 91 Tele-Alarm, SID 27s Seismic Detector or 23p PSU (got the paperwork for these!!!!!)
magpye