VZ receiver cover pin issue

[VZRebel]

Was trying to push the pin out to remove the receiver cover and the pin came all the way out.  Obviously something broke or came off.  What retains the pin from coming completely out?  What part do l need and how to replace it?  Thanks

[RSR]

Trigger spring rear leaf attaches to a long piece (like a thick piece of pencil lead) that sits in the slot in the receiver and holds that rear top cover pin captive. 

Retaining part is in the center here, by the trigger and sear pins (to bottom and left) and below the piston spring (to the top) and beside the bolt catch (to the right):

[VZRebel]

Thank you!  So to replace it do l simply press into place from the top of receiver?  Thanks for all of your help.

[RSR]

Make sure you trigger spring is in its proper place and that retention pin is resting atop it.  You'll need to slightly depress that retention pin while reinserting the top cover pin.  Probably wouldn't hurt to hit the top of that retaining pin with a bit of gun grease if you have it handy as well as the shaft of the top cover pin before reinstalling.