Hi sparkymarka. I managed to fish out that post you mentioned. Turns out that the output type for the bell had been changed to 19 from 14. I must have changed this without realising at some point when I was trying to delete or add the bell when I moved house.
I also added some masking tape to the screw heads in the door contact for good measure.
Problem solved!
Thank you all for your help and suggestions.
I also added some masking tape to the screw heads in the door contact for good measure.
Problem solved!
Thank you all for your help and suggestions.