Weird amp problem accidental fix hack

[LITTLEWING]

I acquired a Stagg 40 watt combo just for indoor use and to chuck in the car to take to quiet rehearsals when recently a switch to swap two pre amp channels suddenly stopped switching and stayed stuck on one channel only. Long story short, removed push switch, tested fine, replaced on pcb. On refitting the pcb to the chassis I left most of the fascia knob fixings loose just to check if all was working. Not only did the push switch now work intermittently, annoyingly there were a few hums and buzzes going on. In a moment of thinking about binning the damn thing I refitted every washer and nut down tight to every knob and suddenly everything went quiet and it all worked 100% including the dodgy push switch.
Thinking about it all afterwards, all the control knob fixings were quite loose on removal which was evidently not making a perfect circuit for everything on the metal fascia.
The moral of this is, if your amp is playing around unexpectedly, it’s worth whipping your knobs off and tightening your nuts up before calling an amp tech.
Every day’s a school day!