Ok, so the blades engage but cut unevenly with the deck at its highest setting. When I go to any other setting the blades don't cut.
I assume its a deck problem. I have located a missing bolt that seems to connect the deck to the height adjustment lever via a piece that has a large oval space with jagged teeth. The bolt threads into another piece that is hooked to the mechanism with a pin.
Is this most likely the reason the blades do not engage on lower heights? If so, why do they engage on the tallest setting?
So, I found a bolt and washer...not exactly the right ones, but they work. I also replaced the drive belt, hoping that was the problem with the blades engaging.
Got everything put back together, and it's as good as new!