Quoted from snakesnsparklers:vireland just posted a nice write-up to correct this design flaw
https://pinside.com/pinball/forum/topic/reinforcing-stern-cabinet-legs-step-by-step
It's not so much a design flaw as another Stern overly aggressive cost reduction. Crappier cabinet wood + cheap, underpowered brackets = more potential to split cabs where they're stressed - all to save less per machine than we'll pay to reinforce the cabs with the proper leg brackets anyway. It's stupid.