The mounting plate was trying to push itself through the grass as well as move the scope and it proved just too much for the poor stepper. In some cases, the grass has been over 6 inches tall and would overwhelm the drive system completely. I see two possible solutions - either raise the base by increasing the height of the legs under the ground board or picking up one of those plastic mats office chairs roll on. Since it would be impossible to guess how deep grass might be at some unknown observing field in the future, the mat will probably be the easiest way to go. Drop the mat on the ground, walk around stomping everything flat and then set the scope up.
Second problem is friction.
The Teflon on Formica feels very smooth in the shop, but once you get out on uneven ground, it becomes obvious that Mel and the listserv know best - ball bearings will be needed under the rocker box. More pictures and information after a trip to the hardware store. Third problem is in altitude. The altitude drive works much better than the azimuth drive. What's missing is smoothness of motion during a slew.