What does yellow exclamation point light mean

YELLO and RED mean danger - clogging, not brush turning, overheating, .... it is time to RESET -- turn it all off and let it sit for half hour - that is what the manual says, check the brush that is not clogged up and check the inlet to the hose and where the hose goes into the body from the head unit where the brush is - make sure those not clogged either. Turn it on, push the RESET button on left back side of head unit by the switch that changes height. The reset button is like a circuit breaker - stops unit when overheats, starts when reset. Yello is ERROR, and fix it before it turns red and stops all the way. Cheers!!!