One of the problems of cheap transformers in use in alarm control panels.
"The buzzing noise is normally the transformer screws loose", not heard that one before.
Tightening the screws might give a little help but don't hold your breath.
The problem with transformer hum is the vibration of the plates held with glue that has now dried out.
The only real cure would be to replace the transformer, contact Texecom, find them on the net. (texe.com)
acorn
December 2008