Quoted from Acupuncture:
Not every unit is manufactured the same. I understand that your machine is working as it's supposed to, so hey, good for you! However there are plenty of others that have issues (albeit minor), so saying "mine works great, you're doing it wrong" isn't helping anyone, especially when many members are very knowledge about pinball. With that said, my best guess is the TK ball lock issue is software related because anything less than a lightning hit up the left ramp won't make it in time before the arm activates.
Based on hours of experience messing with this on my my own game, a friend who owns it and has also spent a lot of time on it, and watching several different examples streamed there are very few of these TK diverters that work as reliably as they should.
As for the software issue, I think the the idea behind it is that the diverter goes down quickly so a slow or weak shot that would not make it up the diverter can still make it around the loop (instead of sliding back doing the ramp and risking a SDTM drain which also happens too much). Thus, at least in theory, the diverter could act like the pro in this situation. I agree that there can be timing issues, but in the current code there is no way to adjust this. I sent an email to Stern about it previously, so maybe we will see some software changes to address this. Also several of us feel that the flippers get a little weaker with time making it much more difficult to make the TK lock after 30 minutes or so of play. It is possible this could be fixed in software, but I doubt that is entirely a software issue.
That said there are clearly mechanical issues here also. Tight turns have the potential to lose a lot of kinetic energy and the ball takes ~100 deg turn right before the diverter. The diverter works by essentially contacting the edge of the ball and pushing it against the flexible plastic ramp on the opposite side. This design has the potential for a lot of the kinetic energy to be lost due to deformation of the plastic ramp rather than the ball going up the ramp and there is no official way to adjust the position where the diverter enters the ramp which seems critical. Furthermore, if the ball enters on the inside of the turn more kinetic energy will be lost to the back wall of the plastic ramp. Unfortunately, the design does not make any provisions to adjust the position where the diverter enters the ramp. Even according to the Stern document, the diverter needs to be positioned with very tight tolerances (1/32") and at least on mine it would frequently move after a few games - this again may be related to large forces on the diverter due to the ball pinching action. I've solved this motion issue with tooth lock washers.
Overall I feel like everything has to be just right for the diverter to work, and even when I can get my game to that point it is very hard to keep it there. I hope Stern comes up with some kind of official remedy for this.