The guys at the rental yard have been through this stuff so many times, they try to go slowly . . . and maybe we shouldn't place the on the professionals and look to the dumb cluck (personal reference) who is nodding that they fully understand the instructions . . ..
While sometimes it's just a matter of getting the starting instructions right, often, the controls rental equipment can be complicated than others -- In my case, when I rented a wood chipper not long ago, I became completely befuddled with which safety bar did what, and how they affect the forward or backward motion of the feeder roller, and engage the chipping mechanism.
I jammed the machine and managed to salvage the effort, but if I had just videoed the instructions that were very competently, but swiftly, provided, it would have save a lot of trouble.
In Peter's case, it was the two different activation handles that engage the sod cutter wheels, and the cutting mechanism.
So, to Peter's suggestion . . . when you get to the yard and are getting the low-down on operating the equipment, first, take photos to document equipment condition, but in addition, shoot a video so you can review the operating instructions when you're back home!
That way, you'll never be confused again about how to operate rental equipment and have to make that humiliating phone call to the yard asking them to tell you why the machine isn't running!