Late Type Stanley no 4 Lever Cap

I just picked up a newer Stanley no 4 plane (I estimate type 20) and found the lever to be missing a piece to my eyes. In particular the thin metal shim on the posterior that the cam makes contact with before the chip breaker. This piece which is present on all my other Stanley’s is not present. I don’t own any other planes of this era though, and curious if the lever cap is broken or if they just altered the design in the later years.

Second question would be, if it is missing, will this effect functionality at all?

Thanks.