Power Brake Booster - again

[tucsonjwt]

I put a new Napa check valve and filter on my booster on Sunday and that fixed the booster problem for one day, then I got a loud air/vacuum noise by the brake pedal when applying the brake and I am back to a hard brake pedal and very reduced braking ability. I can't see up there around the pedal lever without removing the A/C duct. Is there something other than the booster itself that could be causing the vacuum leak - I have read about a "dump valve" but I don't know if this applies to our trucks? I have seen the boot sold separately but don't know if that can be replaced or if the booster has to come out anyway. What is the best way to get to the booster from the inside? Thanks.