Pegasus 534 PIR sensor

Muso101

Hi

I have recently purchased a Bailey Pegasus 534 caravan,not sure if anyone can help,since changing the battery in the pir sensor my alarm has gone off 3 times,once in the middle of the night!  I now notice that the sensor is slightly loose,but having trouble
tightening it up as it has a double nut set up and i can't get to the locking nut,any advice as to what I should do would be appreciated,as I'm slightly nervous now about putting my alarm on...Bailey and Tracker helpline haven't helped other than get an engineer
in to fix it...

Regards

 

Chris