how do you kill the pinger (correct spelling of pinger if wrong)

Blow it to smithereens. Use the JAW and sneak up on it with C4. Fireworks will insue.

what about the other ceph

Use your gun to shoot bullets at their heads.

^^^ love that tip

This pinger took me a few tries on Super Soldier. There are a few JAW rockets aorund the area, find those and shoot him with those. Also, I would stealth and get to a safe distance from him, then chuck grenades at his feet. Those seemed to do quite a bit of damage. There are a couple of grenade resupply boxes in the area, too, so if you play it right, you could end up with about 10 grenades. You don't necessarily need to hit the pinger on his weak spot, but it does take him down quicker. I got tired of trying to sneak around the back of him with the JAW rockets, so I just fired the straight at his head, then did the grenade thing, and ended up finishing it off with the M60.

HTH!

wait he did it on super soldier!?

Melee works great.