Heater making cracking/buzzing sound

[68 ss]

Just installed a Tempware 10,000 watt heater is garage (60A, 6AWG, double pole breaker). First day running no issues(ran for couple of hours) ..2nd day..started hearing crackling/buzzing intermittently 3-5 minutes after startup...noise is on/off every 20 seconds or so?? no smoke, no sparks/arcs, still functioning, noise stops the second its turned off.

Loose connections? internal heater issues? HELP?

 

[fitter30]

Check all connections any push on terminals give them a pull. Bussing sound could be from a contactor where there might be some corrosion that is on the laminated plates that come together when contactor pulls contacts in. Then it needs to be replaced the noise will get worse.