I'm having issues with calls being dropped. I have a Merlin Legend rel 6.0. I've had the phone company test the lines from the dmarc everything is fine. I tried replacing 1 of the jumpers that goes from the port on the card to a grounded module. When I replace one of the jumpers I get a loud hum on the line. If I put it back the way it was, I get normal dialtone. Any ideas?