Ruger rear sight question

[Dirtybob]

I have a Ruger MkII competition target with what I assume is the factory rear sight. Noticed today that the elevation hinge pin on the rear sight wants to walk out of it's location. I don't see any clip or detent to keep it in place, it's just floating in there. What's the fix?
offending pivot pin circled in red (not the exact sight on the gun but close enough)

 

[RKRCPA]

Put a slight bend in the pin

 

[Bazoo]

It's a common problem for Ruger rear sights. I actually take a punch and put a very slight flat spot on the pin. Not on the end, but in from the end about 1/16". Then when I drive the pin in, the end still looks good.