Scotch locks, you'll be lucky, I've seen some where they just been twisted on to a stripped wire, no solder or locks, if your lucky a bit of tape. He bought the components for a pittance, flogged them on the forum for a fortune and fitted them as if Stevie wonder did your audio install, took the money and then fooked off abroad. I did express my concerns at the beginning when I pointed out he was using illegal software etc and was told to mind my own business. If you want to fix it, you'll need to completely remove it, it could just be one of the pieces of bluetac has fallen off 2 joining wires. Dismantle and rebuild using actual solder might fix it. Insulating the wires might help. Properly grounding it might fix it. Could be any number of shoddy jobs.