Can someone tell me how the orientation arm locks the spindle in place? I have a 4020 that I am apparently rebuilding one thing at a time and the spindle doesn't always lock in the exact same place. The variance is only a little but you can sometimes move it by hand a bit until it locks (maybe 5 degrees of rotation or so), then it is positively located. This is causing the turret to occasionally not locate properly on the spindle keys. I know on my 15XT the spindle has always made a solid "clunk" when orienting since new. The 4020 makes no sound at all. It just slows down and then stops....sometimes on location, sometimes not.