I have a Bagg Element pickup installed in my Gibson CJ-165 ... I have suddenly lost the output on the low E, A and D strings, G B and E strings appear to be okay. (i am basing this conjecture because my DI gets a tuner signal from the high three strings but not from the lower three.) This may have coincided with a recent string change, but the bridge itself was not disturbed. Any troubleshooting tips?