The springs are visually fine they do sound different like more hollow
and i mean that the edges of each key dont register ( i have to slam these keys dead center or find a unaffected edge to get it to register and some times the key click only comes on the upstroke
not sure what the issue is not my vido but nearly identical concern
It sounds to me that the caps may need to be seated properly. Try what's done in this video a few times. I haven't watched the whole thing, but the part where the board is basically pivoted 90 degrees and placing the caps in place with it oriented like that should apply to Model Ms as well. If that doesn't work after a few tries, it wouldn't hurt to look at his other videos, or others on Youtube, about removing the springs and maybe flipping them upside down, etc, pressing them firmly down with tweezers, etc.
I'll take a look at one of my Ms when I get home.