Using pcfsyg:~/pcalmon_dim.sh for testing.
Summary: CoMo B still shows low phase cal amplitude, about 20 units compared to ~40 for CoMo A on the same settings. Eliminated X-band inputs as the cause by swapping them. Given the old CoMo B and the new one behave similarly, it seems likely that the CoMo is not the problem. It could be the IF cable from the output of the CoMo, so we'll swap that and see if there's an improvement….