Ok (sorry about the slow reply)-first-
" remove the dipswitch wait a while and reverse above and see if it is any better is that cured it good if not enjoy your ebay experience"
*** not so good. Ebay time? what are we hoping to do.... ? Doesn't that just make sure we've done a hard reset, a full power down?****

Second question-
"When you swap phones, problem follows phone or problem follows port? Or does problem occur on all ports?"

***problem occurs on all ports that have lines attached EXCEPT CO #5 (usually)... which is a single line port. We use CO's 1-6, seven and eight are unattached. Considered splitting up the dual pairs (1,2 and 3,4) thinking it may be a port problem, but don't have enough single ports to hae them all plugged in at once. (Doesn't seem to change anything when I move single 5/6 to single 7/8 anyway... seems to be a problem in the dual port inputs... because it still happens on 3/4 when 1/2 are unplugged, and on 1/2 when 3/4 are unplugged... and those are all on the main board, right?

To prove that it was not a single phone / line combination that was creating the weirdness, I moved the keyset phones from line to line, and tried it out with all in house lines unplugged except the line to whichever phone I was using. Same results, on each line I tried... no matter which phone was on the end of that line.

"Really stupid question: Are all of your amphenol cables off of the KSU attached tightly?"

Yep. All the RJ connectors look good. Pulled them out and put them back, several times, they're all in properly. Don't see any burned ones / loose ones. Checked out the punches where they split from the CO bundle to the 66blocs, too... just in case.
Jason