sudden no brake assist? 91 caprice..

Oct 6, 2014
I think i've had a loss of brake assist from the vaccum booster on my 1991 chevy caprice classic. (about 222k miles) I suddenly got a rock hard pedal for a few seconds the other day, which passed, then it drove fine so I just drove ultra-carefully pre-testing the brakes and leaving alot of room. Today I started it up and the pedal is very hard and doesn't want to brake... it feels like its trying to help a little but then goes back to a hard pedal again.

What I thought was wierd was there's no Brake or ABS lights on, but I dont know if it watches for that with only being idiot lights for common conditions. Being 32 years old might there be lines to the brake booster failing independantly, or is it safest to assume I just need a new brake booster? (is there likely to be another cause of a failure besides the booster itself to try to diagnose or to possibly inexpensively fix)
There is also a filter (i always thought it was a check valve) at the brake booster which wouldn't hurt to check to see if you can move air through it.
If the booster is leaking, you should hear it. Otherwise, make sure there is vacuum applied to it. Check the large hose going to it, its check valve and the grommet which the check valve plugs into.