i have used at least a dozen of those kit, and have had only the occasional issue. Like it was said, it is worth adding a small washer between bat and bushing though i haven't done it on most game and it is fine. Making sure the L bracket is raised/bent so the plunger doesn't push through is a good one as well.

Once i had an issue where it was just weak due to some resistance somewhere, i assume it was a slightly larger plunger defect, replaced that part and it was fine.

I only use Stern appropriate bats with my assembly.