rust master,
I have driven many trucks with hydrovacs...they shouldn't work as you have described. If they sit for any length of time, the brakes are touchy when first driven. I have always attributed this to dampness or light flash rust on the drums. The pedal feel should be almost like a conventional vehicle...no hard spots or binding.
I used to have a Midland-Ross troubleshooting card, but i can't find it. I did a search using 'Bendix Hydrovac' and found their troubleshooting guidelines, but didn't see your problem listed.
Something isn't working properly...I don't know what. Good luck and keep us posted!
Stuart
