I messed around with this quite a bit and now mine works! 100% , on the owners thread about the page 58 I posted some pics of what I did.
I can offer some suggestions that might be helpful.. as far as I can tell there are 3 common drop target issues , the difference between working and not is small like 1/16 inch or less !
first try to figure out what the target is not dropping!! on mine and on most I suspect it is because the actuator nub on the trigger plate ( the piece with the red arrows above ) is not pushing the drop target off the retaining ledge with the added force of the ball behind . you can hear the coil fire but the target stays in place. if you take a pair of needle nose pliers and slightly bend the nub towards the drop target so it is just shy of protruding above the retaining ledge it should fix it . while doing Anchor the coil relay (magnet ) portion (right red arrow )with another needle nose so as not to change the angle on that side of the plate ., I ended up gluing a piece of plastic to the target so less travel is required by the trigger plate but this probably was not necessary
if the coil relay portion of the plate is too far away from the magnet, the plate will not move at all , you will hear a soft click , and can see that the trigger plate is not being pulled in if you activate with the playfield raised, , so you will need to bend the coil plate section closer ( right arrow) to the magnet, anchor trigger section with needle nose as above, it can be a little tricky bending the plate as if you do not have it firmly anchored the you will change the other tigger sides angle as well . I learned this! I ended up putting a washer between the the coil relay and the bracket to close the distance and it accomplishes the same thing as bending the plate
if the target does not stay up either the actuator nub is protruding too far or the target is not catching on the edge of the retaining ledge, stern had a fix for this for other drop targets which consisted shimming the ledge with a thin washer to make it protrude a little farther. I have seen posts of people making a shim from a credit card to do the same thing.
I talked to stern and given that I was the second owner they did not send me a whole assembly but did send me a new trigger plate , looks exactly like the old one!
if any one got a new assembly that looks different from the old one would love to see a picture