Looking good, Brad.
I'm sure you are doing this, but whenever you add a new row, make sure you rotate the turning as if it were a turntable and look at it from all four angles. If the plunger was solid and mechanical driven, it would be expected to be always in perfect alignment. Of course, the cost would be several hundred dollars as well. As it is, the sprinkler-based plunger works as intended, but you always have to double-check the joint alignments.
I'm anxious to see more progress.
Lloyd