When I got my Judge Dredd the targets were like this. They were simply gunked up so I took the assembly apart, gave them a good clean then applied some new lubricant. If it's not that they are dirty, then my only advice is to pull the assembly out and pay close attention to how the parts are interacting. Observation will show you what is happening then you can remedy it.

What title are we talking about here? The target bank can be shifted a slight bit forward, so there is more space behind the targets where they go thru the play field. That way, they can drop back farther and at least on all the Gottlieb games, are easier to drop. AD's advice is good too. Make sure they are not gunked up/binding anywhere else.

Guessing from your collection list this is Gold Strike? (Since Spin A Card has no drops.)

When the drop targets are hit and the spring starts to pull them down, the lifter arm has to work past the switch stack that's pressed against it (underneath the playfield and behind the drop target assembly).

The switch blade that rubs against the lifter arm often gets gunked up, and/or the blade has a bit too much pressure on the arm, making it hard for the arm to pass by on just the spring tension.

Cleaning off the gunk, and then applying just a very light dab of SuperLube along the blade may be enough to resolve it. Lessening the pressure of the blade against the lifter arm may also help (but if adjusting the blades, make sure the contacts are still opening and closing correctly).