@Martha: What version of kstars do you run? L1P was added in July (git), and was in the 3.6.0 release, so I had just assumed most people run it by now. My fault . No worries, just keep in mind to test it once you update to something >= 3.6.0

As for measuring backlash:
Make sure the BL compensation in the driver is off.
Do two focus runs (with linear), note the average value. Then go to the INDI tab of the EAF. There's a 'Reverse Motion' Button. Toggle that, and repeat the focus runs, twice again. The difference of the two values should be a quite good starting point for the BL compensation.
If clear sky is too expensive to waste you can also do it inside, but you need a good caliper. Just step the EAF in one direction in small steps, and with each step measure the position of the focus tube relative to the OTA. Once the change is linear, step in the other direction, again noting the focuser tube position. Continue until that one changes linearly.
If you plot those (position vs. EAF reading) you should see two straight lines, maybe some deviations in the start and turn area. Draw a horizontal line through a region where both are linear, and look up the EAF readings for the two positions were the horizontal line crosses the two sloped ones. The difference is your BL.

Read More...