Fixing Pitch Wheel Detent?

[thetraintomars]

I have an old Minimoog, I think it is a 74, and there is not center indent in the pitch wheel. Was that something these units had, or could the one in my Moog be missing? My searches came up with info on the reissues only. I'd like to fix it at home if I can, I am hoping it is not a difficult fix.