In service bulletin 165, Stern Pinball suggests fixing drop targets that won't stay latched in the up position with a washer or two between the drop target mounting bracket and the latch bar, or ledge. (More info at https://pinside.com/pinball/forum/topic/star-trek-le-drop-target-wont-stay-up#post-2073538)

In case your ledge/latch bar is broken like mine, or in case you'd rather have solid plastic instead of washers & plastic, you can use this. It's about 1.5mm thicker than the original, and solves the problem nicely.

Printed in PLA and it seems fine. ABS is probably better. Solid infill at .15 layers took about 8 minutes on my i3.