On the Century CETMEs, (and G-3s too) have him pull the bolt and carrier.
Seperate the Bolt and Carrier and look at the surface of the rear of the bolt and front of the carrier.
On many of the Century guns, the
Damn Dirty Apes at Century just GROUND the surfaces down to try and correct worn headspace. The proper method is to instead invest 15 minutes and 15 dollars to insert the correct +2 or +4 replacement rollers. But would Century every do it correctly??? in my experience - Sadly NO!!
A Ground gun is worth much less, since that fairly screams "Head Space Problems", "Shoddy Century Assembly" (evidently by minium wage chimps), and "No One Gives A Crap Quality Control".
There is a long tack on this in the CETME files on the internet. I've lost the URL, but you should be able to Google it up.
I've bought several Cetmes for $250 off the E.E., so I guess the key question is how experienced the buyer is. Some Newboob at a Gunshow or Gunshop may pay $450 for a Century CETME.
BIGGER_HAMMER