Where do I find the air intake screen on a State Select Water heater and how do I clean it?

The air intake will be on the heater its self if it is a standard vent heater and not a power vent,
Look and see if there is a plastic screen below the burner area near the floor, if yes remove it and the air intake is in there. Good luck, Tom

Thank you. I am pretty sure that it is not a power vent. I will check out the plastic screen.

What is the problem with this heater?