I’ve been playing with an Underwood pickup through a used PJB for 6 months with good results. This week, after an hour or so, the signal weakens then dies. With the same cable I can then plug the same bass and pickup into an old Trace Elliott and it works great. Additionally, my passive Fender PBass plays fine through the PJB just after the DB loses signal. I tried it with another passive pickup with the same results. Any ideas for what the issue might be would be greatly appreciated.