Ok rebuilt master cylinder on 1941 3/4 ton with kit from dcm,obviously mc needed it after 20 years no activity,wasn’t horrible inside but honed and cleaned and rebuilt,than did both rear cylinders,that said I’m gonna try it added fluid and and starting pumping to bleed,but no matter how many times I pump it never builds pressure,don’t notice any leaks,I can hear internals going back and forth,but no pressure,didn’t bench bleed,but what should I try look at and try I’m very confused usually you get a little pressure but nothing,any help appreciated