Whenever I have need to check the backlash of my mount or possible PHD/mount problems I use free GPINtCheck software. The version I use is for mount driven from a parallel port but I understand that there are versions to suit other interfaces.
The advantage of using it is to bypass PHD control and cause directly movement of the mount by use of the PC's arrow keys. The mount movements are small so I observe them by taking the cover off the gears of my HEQ5 Pro mount and observing the movement of the cog wheels.
https://en.freedownloadmanager.org/W...heck-FREE.html