Quoted from akm:Hey guys, any tips for drop targets on the earlier classic Sterns? I have a Memory Lane I am trying to get dialed in and just can't get the drops working right. The ball will more often than not bounce off the targets (without them dropping), or the drops will go down on their own when the game kicks them back up. Really kills this game as they are a pretty important feature. Replaced all three targets and as far as I can tell, the mechs/springs/etc look fine.
Do the replacement drops have the rib on them or just the shelf right below the target face? Rib is correct for Memory Lane, and 'chichlet' style (no hood).
The ones that are shelfs are Bally style drops and they brick exactly as you are describing.
Since the drop bank is straight on they will tend to brick a little bit, Lightning's center bank is terrible this way and ML is likely similar. You can try and move the entire bank forward as much as you can and people have tried stiffening the drop to help its downing, but it tends to be a losing battle - it's endemic to the game because of the angle. Gottlieb drops are the only ones that don't brick straight on.
Higher flipper strength doesn't help either.... someone a long time ago did a slo-mo video of drops that wouldn't drop and the reason they don't is that the target flexes and hits the back of the slot with such force that it comes back front onto its shelf rather than dropping. Stronger springs help but then they don't reset properly.
If you look on rec.games.pinball there's a lot of threads where people played around with this, as well as likely here on pinside.