I do not have the owners manual - what is the step by step process to remove the deck- I need to get to the solenoid that release the blades. I can see the cable and spring moving underneath, but the solenoid(I think) does not put tension on the belt

Hi,
A solenoid is an elecrical switch using a small current circuit to swich a large current circuit, so I would doubt that is it.
That 9 digit model number (it begins with 917) under the seat will get you the manual at Welcome - Managemyhome.com and it is detailed in the Service and Adjustments section.
Peace,
Clarke