The sear (the white metal bar in the pic that fits in the recess in the bottom of the action) has a very strong spring holding the contact surfaces between the sear and the trigger together. Something was amiss with the retrofit or aftermarket trigger/sear install done on the Springfield. Unless one has knowledge of trigger fit, function, theory and sear angles- only qualified gunsmiths should mess with them. I have no idea what trigger replacement was used and failed the drop test. IIRC Rifle Basix is/was one of the companies making Mauser type after market triggers that would have also fit both the Springfield and the Win M54.
Reminds me of Remington's woes with the adjustable box trigger in their Model 600s and 700s. A few adjustments here, a little monkeying "tuning" the trigger there, no knowledge what over travel is much less how to set it correctly in any trigger, a few accidental discharges along the way and voila no more Remington- no company, no more. Same with the original style Win Model 70 trigger or any trigger for that matter. Make a mistake and oops ..... The "new", post New Haven M70 Winchester trigger, is also a box design but factory preset. I had one of the early FN Win 70s but was not at all impressed with their new "MOA" trigger. I no longer have the rifle.
The Springfield trigger was based on and nearly identical to the Mauser 98 trigger. Not adjustable and nearly a mile of creep. One of the reasons the US government had to pay Mauser for patent infringement was because the Springfield design was so close to the Mauser 98 including that trigger. Those are basically non-adjustable triggers/sears that engage on the striker lug at the bottom of the bolt. The same design was maintained on the Winchester Model 54. Post Model 54, the Winchester Model 70 design team came up with the Win Model 70 trigger as in the picture. When FN acquired Winchester and moved the factory, they again redesigned the trigger to its current box form called the "MOA" trigger. But let any enclosed box trigger on a seriously used hunting rifle accumulate years of oil/grease caked crud or rust or corrosion then resort back on flawless function of internal trigger parts