Why is this drop target coming out of its slot?

So I put in some new drop targets. I noticed this issue only because I took off the playfield plastics above the inline drop targets. The game/target actually works fine when the plastics are on because the top of the target hits the plastic before the target can derail. When the plastic is off the target is able to shoot up too high.

I can't figure out the different between this one and the other two which work fine.