We've got a Hyundai 30M Lathe with C axis. It's been fine & never been crashed, I know as I've been the only person to use it since new. Lately we've been havely problems with the live tooling not stopping in the correct orientation before trying to index the turret. We have checked the turret & re-aligned it as it was out after it tried to index the turrent whilkst the live tooling drive tang was in the wrong position, it still does this after re-alignment. It has a Siemens 840D controller,siemens electronics & a Duplomatic ODT-N turret/live tooling setup. The drive tang is just a simplt rectangle tang that fits into a slot inside the smaller pinion that is driven off the big ring gear. I am guessing it's a sensor error/encoder error as from what i can gather there is a position sensor on the front of the motor drive & also the motor uses an encoder, sometimes it will orientate to the correct position & other times it won't. Been back to the Hyundai people but with no luck, been back to duplomatic before we had this problem & they seemed helpful & I may have to ask them again, but thought I'd ask here in case someone has experienced anything similar as I'd like to fix this but have limited downtime to do so.