Check the loop current to see if it is running hot. I like to see between 28ma to 35ma but a little lower is ok. When it is too low (18ma or so) you will have disconnects and much higher causes other problems. If you search Loop Current here you will find quite a bit of discussion on line current levels. I see you have Executone listed in your signature line. I once had on old Executone CX that quieted right down after installing 100ohm resistors in place of bridging clips.

- Dave S. -

You can never appease your ideologue opponents.