Quoted from colonel_caverne:
What is the best way to hit the right facehugger (mini loop) and the chestbuster?
Do you succeed to shot chesbuster with left flipper consistently?
Right Facehugger (Vent 2): either from the upper left flipper after a saucer eject, or from the lower-left flipper by aiming for the weapon target above that lane, or even from the LL flipper by aiming for the right side of the post at the tip of the upper-right flipper -- that ricochets into Vent 2 more than you might expect.
Chestburster: either from the upper-left or lower-left flipper, as you'd expect. Both are possible, it's just a tight shot. (BTW, Vent 1 -> Chestburster is called a Host Combo, and is kind of like an End of Line Jackpot on Tron... can be rather valuable.) If you haven't already, I'd suggest going into adjustments and turning "Chestburster Lane Difficulty" to Easy... this eliminates the requirement to actually hit the standup target, and allows just the inductive switch in the lane to award this shot. It's only a couple centimeters difference, but in my experience this makes it a fair bit easier.
As for consistency of hitting the Chestburster... once just for fun I tried it 100 times in a row and tallied my success rate... I got right around 33%. I don't know what the success rate for an "average" shot is, but I'd consider the Chestburster to be fairly difficult but doable.