Evaluating Reel Motor Speed

We have been experiencing an inconstancy issue with the quality of cut of the intermediate and surround mower.  The outer left unit is not producing the level of quality cut that we expect and leaving a plateau appearance on the turf.  In the troubleshooting process we verified reel to bed knife relief, height of cut, bearing movement, and reel to ground speed ratio.  Next on the list was to verify individual reel speed and hydraulic motor efficiency.  To measure this a digital infrared tachometer is utilized. (Pictured below)  We discovered that the suspect unit was underperforming and will require further diagnostics.