First, thanks for continuing to respond with help. I went back to a speed of 1 taking 1 step at a time in the loop. I checked the arm's movement with a magnifying glass. Can't say the movement is consistent. It does not move backward. The forward movements are regular in time but not in distance. I can't pick out a pattern. It seems random and I suspect this may be due to the slop between the gears. When you previously suggested switching pins 9 & 10, I switched them in the code. Is that ok? - Scotty