OK this may be a dumb question, but since you put a channel bank in I have to ask. Is this D4/AMI or ESF/B8ZS. The reason I have to ask is if it's D4 not seeing errors doesn't mean anything, the only time it will regester an error is if the error is at the same time as the check bit. The circuit must be taken out of service and tested ESF to seeing if there are errors or not, monitoring won't do the job.
Bill


Retired phone dude