There is a strong possibility that gun was manufactured for Sears by High Standard.
I just repaired a JC Higgins Model 31 .22 semi auto. (High Std) with the same issue. The part that fails connects to the bolt to reset the trigger and related linkage.
Numerich gun parts number 361370, Disconnector Assembly.
Some minor filing, fitting and patience is required.........but it works and now shoots like new.
When I removed the trigger assembly from mine the broken tab was lodged in a void behind the bolt. From what I found out this is a common problem.
Check with Numerich for a schematic and verification of manufacturer first.