I was getting erratic IR engraving on metal plant stakes yesterday - it wouldn't engrave consistently at various areas of the baseplate. This morning I was using the IR to engrave large plant stakes and the IR was perfect through 4 of these items, then suddenly, it engraved a “P” on the 5th one, then stopped and wouldn't engrave anymore. Tried turning the maching off and on, no luck. 

Has anyone encounted this? Is it likely a control board or something? The blue light is working fine.

Thanks for any help.