If you have an old recording which has a good view of a shaft, you can open it in Version 2.5 or newer of Motion Explorer and add one of the Shaft Measurement ROI boxes (Horizontal Shaft or Vertical Shaft) to the shaft location. Keep in mind, the shaft must be large enough, have good lighting, and be either horizontal or vertical. If you only have a small portion of shaft in the background, it may not provide good measurements.