I have a BCM50-5.0 with (1) PRI installed and continue to get Alaram 75. Have done all the basics, tested with carrier, switched feed pairs, switched cable to DMARC/SMART JACK and even swapped the DTM. We now have the circuit relatively stable, but periodically we are still getting Alarm 75. One question I have is, can anyone confirm that the clocking source is located on the BCM50 main chassis like I think it is? Any thoughts as to other tests or fixes we can try besides swapping the expansion or main cabinets?Thanks,