I have a Yugo underfolder and when I was "going thru it" yesterday I tried to use the vent tool to push through the gas block vent hole and into the barrel as I have been able to do with other AK's and it doesn't go.
Is there something different about the Yugo gas block or is it just plugged? I have fired it and it functions flawlessly but with other AK's I've always been able to push the vent tool or brush or even a pipe cleaner through the hole and it's visible in the barrel. This rifle has been chromed, but not inside the gas block itself.

Any thoughts?

I think that lifting up the grenade sight operates a gas cut off, to prevent the action from cycling when firing rifle grenades. Try again, but leave the grenade sight down.

I think you are probably right. I normally wouldn't lift the grenade sight but I changed out the hand guards and I'm sure the sight was up. Man, this is a great site with very knowledgeable participants. I've never been let down.

Thank you