My TCL160 with auto change tool turret runs original cad/cam design tools V10 from Boxford, build 3, so it's quite old. However, when the machine is unpowered (switched off), there's some radial play in the tool turret. When switched on, this play disappears and the turret is rigid against the pawl - whatever the tool position.
Rotating the turret : The turret always advances beyond the final rotational position and then reverses hard against the pawl. I believe that current to the stepper motor is maintained and thus the motor is stalled, I believe this to be common practice but the current is somewhat diminished to minimise motor overheating, presumably by software. One minor oddity which may explain the different number of steps required to reverse against the pawl....when the turret advances to a normal shanked tool position (eg a turning tool) it advances only just over its final position and then reverses to lock, however, when advancing to a 'drill' position it has to reverse a little further. I assume this to be the need for the shanked tool to be on centre, which means the top side of the shank, in line with the cutting tip at 10mm, needs to be on the lathe axis, but the drill bore axes, if equally distributed around the turret axis with respect to the shanked tools would have to reverse by an extra 5mm (radius of the drill bores) to be on centre. This would account for the extra reversing required for drill tools.