Index the turret repeatedly and measure the X/Y positions of the tip of the tool. There was some problem with the first generation turret; can't remember if it was a reliability or a repeatability issue.
Do some test cuts, and mic them to see how close to the programmed cut they end up; this will give you some idea of backlash.
When was the machine originally purchased?
Look for indications on the turret, QCTP (if fitted) and chuck for any crashes.