Hi Ken,
I'm not a expert on these mowers so I can only tell you what I've read.
Normal Operation: It is generally expected that when the motor starts and the pulleys rotate, the belt connected to the reel may show some movement or rotation even while the mower is at a standstill. This can happen if the belt is properly tensioned and the pulleys have minimal friction. However, the belt should not rotate fast enough to cause any significant movement of the reel or drum when not engaged.
Belt Tension: It's important to ensure that the belt tension is appropriately set. If the belt is too loose, it may slip on the pulleys, which can lead to movement without properly engaging the reel or drum. Conversely, if the belt is too tight, it could cause excess wear on both the belt and the components. Adjust the tension according to the manufacturer's specifications for optimal performance.
No Creep: The fact that there is no creep from either the reel or drum is a good sign; it suggests that the belt is not overly loose, and the engagement mechanism is functioning correctly. Proper engagement means that when the belt is meant to drive the reel or drum, it will do so effectively without any unintended movement.
Cheers
Max.