Out of five top element heaters two are not working properly.
Left front heater does not heat at the moment. At some point I was able to turn it on but it was shutting off randomly. Also had case if I start left rear small heater left front starts working as well

!?
Right front now started acting also on its own. It shuts off completely after 5 min of heating so it is not possible to cook reliable anything on it.
I was thinking that maybe
Range Relay Control Board Assembly could be the culprit but also
main PCB due to the fact that two of heaters started with one button at some point.
I tested resistances on all heaters and according to service book found in the back all of them are within specs ( actually all are ~4Ω less then specs)
Would like to hear opinions.
Range is LG LRE6387ST
Thanks.