Is This normal? Blowing brake boosters

[nrb's70gmc]

Quick rundown i baught my truck in 2001
i replaced the brake booster that i baught the truck with,(it failed) (around 05-07) cant remember exactly what year. it was a napa replacement booster listed for a 1970 gmc 2500.

ive been having a hard brake pedal for a few months now. and braking perfromance sucks.

when the brakes are acting normal i can lock them up (not possible now)

i checked the vacuum line
i pulled the line off the booster and hear the air (motor almost dies-plug with thumb) and retures to idle)

it seems to me i need a new booster. is this normal replacment (in years from when i replaced it before) or is it premature failure?

[notsolo]

Quality of replacement parts is not what it use to be! ....Bought some front brake hoses from Napa a couple weeks ago....Chinese crap....I would think a booster would last 20 yrs.

[Liteman504]

An easy check for brake booster is to hold your foot with pressure on brake pedal. Start engine ,if pedal goes down further when engine starts the booster is working correctly.
T