I installed some used Whelen PAR36s on a PD Charger and recently one has chosen to stay on steady burn. I checked it out Friday and all the connections are secure. I took it off and bench tested it and had the same problem. Thing is, when I clip the P/W wire to the power, it flashes normal. It won't sync with the other light, and sometimes it changes patterns but otherwise functions normally. Any ideas on why this is? I think this a first-year light so it's out of warranty but I was still thinking of calling Whelen to see if they'll work with it. Can't hurt, right?