I have tried cleaning all the jack plug sockets with contact cleaner but that didn't work unless maybe I need to repeat the process several times.
Badly oxidised sockets may need cleaning up to 9-10 times. Pay special attention to the switching jacks - headphone, FX loop, & Line outs (but especially the first 2). These can stick, preventing a clean contact and deteriorating the signal thus resulting in crackles, hiss, distortion etc. This is THE single biggest issue with Valvetronix amps, but its also the easiest problem to fix - just needs some patience.
The other thing to try that's free, quick & easy is an amp reset back to factory settings which will usually fix any glitches caused by software filepath errors.
It's all explained here: