If you can get me the model number on it I should be able to get you the documentation available for that unit including a parts list, let me know.
The model number is UGPH12EARJR
If you can look through here and give me an idea of where you are doing this at to get it to run , the area I thought you were talking about is where the circuit board ( integrated furnace control ) would be, let me know. Also If I can also get the serial number I can be more specific on what you have as this came with many variations that are denoted with the serial number, sorry about that i did not know that when I asked for the model usually that's all I need.
The round part I pluck is behind the burner compartment door. The serial number is FD5D307F250212921
I can't figure out what you are starting by hand, is it the vent motor ?
Is it possible that you can take a photo of ti and post it here ?
That's the air pressure switch. I probably should have guessed that.
You will need to replace it. It is part number 10 on the parts list, you can tell the gas service man that you need the air pressure switch or draft proving switch. Rheem / Ruud just calls it the "pressure switch.
I believe it will, let me know how it does, this is not an uncommon repair.