2008 Altima Brake Booster Check Valve

[bausa]

Trying to locate the brake bootster check valve on my '08 Altima (2.5L).

Followed the rubber hose coming off the booster to the back side of the engine. Only thing spliced in the line is an aluminum line attached to the firewall.
Coming out of the booster is a plastic 90 degree elbow, but doesn't seem to be a check valve unless all the guts fell out of it.

Anybody know where to find it on this model? Local Nissan dealers are usless. They tell me they can't find it on their schematics, and won't let me talk direclty to a mechanic.

Thanks.

[bausa]

Update -

After waiting 3 days for the local Nissan dealer to call me back........There is not an external brake booster check valve on the Altima. Check valve is internal of the booster.

I'm really don't want to repalce the booster. My idea is to splice in an external check valve into the rubber hose leading from the booster to the rear of the engine.
Would this be a viable option to try, or is the booster entierly shot? Brakes work fine when the car is running.

Thoughts?