Problem(s) Encountered:

We took the telescope about 1000 counts out of focus for a throughput test at the beginning of the night (to 9025). When we slewed away from Zenith to our first target, we noticed that we had lost the ability to adjust the focus (to our nominal 8025).  We tried adjusting with both the GUI and the hand paddle, but it remained unchanged. Spoke to Eric and tried changing the position of the telescope (to troubleshoot a loose connection) as well as restarting software, rebooting the computer, and cycling
the MDC rack. We did not recover focus control after any of these steps or throughout the remainder of the night. 

Solution:

The armature for the Renishaw encoder was ~0.25cm out of alignment.  I realigned it and all started to work again.