Server 2.9.2 (or possibly connect) Backlash became forward-lash

Bug report

Summary

Using version 2.9.2 on RPi3, the backlash compensation does not operate correctly.

Configuration

I'm using:

Camera: Raspberry Pi camera v2 Motor controller: Arduino Nano Server version: 2.9.2

Steps to reproduce

Set step size to 100 in Connect local on the Pi for x, y or z

set backlash to 1000 for each axis through settings in Connect locally on the Pi (the green 'settings applied' box comes up)

Press the arrow keys to move forwards and backwards in x, y or z: one way will move 100 steps, the other will move 1100 steps (or at least a long way. It does not move 1100 then back 1000.

Additional details

Backlash operated correctly on this microscope on 2.8. Version 2.9 done as a fresh install of the SD image, then ofm upgrade to 2.9.2 In my microscope axis y is marked as reversed in Connect. x and z are not reversed.

/cc @jtc42