Well,
Once again I've proven that there is no finite number of times I can be wrong about something.
Nothing wrong with the alarm panel, except my diagnosis.
Moving all the SLT's after the line card cleared the problem. Also made the voice quality on the 2565's better (There used to be an intermittent scratching sound on them).
Many thanks Arthur.... I'll be implementing the A lead control as soon as Mr. $ says OK. Ed previously pointed me to sandman as a source.
Thanks to all -
Matt
