no screws on receptacle

[dkpbxman]

Yesterday, part of a circuit went dead. The problem was traced back to a loose "backstab" connection. When I pulled out the offending receptacle, I saw that there were NO screws on it at all. Only slots for backstabs.

I replaced it and now am inspecting all the other receptacles in the house but I was wondering, was this common in the early 70's when the house was built?

EDIT:
I'm sorry there is a ground screw

[HayZee518]

the brand EAGLE is reknowned for screw-less receptacles. All they had were pigtails coming out the back. EAGLE also made back stab "quick-wire" receptacles that HAD screws.

[Speedy Petey]

Backstab only receptacles were popular in the 70's. The problems started arising shortly after and continue on.
Even if they had screws it is likely that they could stand replacement anyway after 30 years.