I recently rebuilt the upper right flipper (new coil and sleeve, new springs, new prawl, new bat/rubber) and I find getting up the Delta ramp much, much easier now. I was getting up it and to the Borg ship fairly regularly before, but it would usually require hitting the ball as it's coming down the playfield to get the best speed to make it. Now I can make it up the ramp and to the Borg ship almost from a standstill where the ball is just hovering or moving very slowly near the upper right flipper bat.
The hit ball speed up the ramp is now way faster than before (which I initially thought was great). However, I've since noticed that about 2 times out of 10, the ball gets kicked back down the Delta ramp after hitting something when it turns the first right corner....and I think it's the divertor arm. I can't quite see it when it happens as it happens so fast and I'm usually still looking at the upper right flipper after just hitting the ball, and I've been unable to capture it clearly on video so far.
Could too fast of a ball speed up the Delta ramp mess up the timing of the divertor activation? I cleaned all of the optos a few months ago when I did a teardown/shop job, so I'm pretty sure the opto switch is ok. The new coil I put in is the same part number as the original OEM, i.e. not a bigger spec'd coil.