[dsraven]

first check all the linkages to ensure free travel and no sloppiness. check to ensure there is a return spring to bring the pedal back up all the way.
next check for pushrod free play to ensure the master isn't being held with brakes slightly applied.
check to see if there is a residual valve built into the master and also an inline one. too much residual valve pressure will give you problems.

try bringing the pushrod travel to an extreme so there is for sure free play, then apply the brakes and ensure the pedal comes back all the way. now check if the brakes are still applied slightly. if so then it isn't the linkage so it must be hydraulic. start checking for the proper port for each line etc. if it is easy to see inside the reservoir you can check if the piston is returning all the way by looking inside the res when the pedal is pushed. there should be a little fountain of fluid right when the pedal is pushed, then the fountain goes away as the pedal is pushed further. this is because the master cyl piston travels back further than the supply holes in the cylinder bore so that fluid can return to the res ( from heat expansion for one reason) and also so fluid can flood the piston bore when the brakes are released or pumped. when the pedal is first pushed there is a slight time when the piston hasn't gone past the holes so a little bit of fluid "fountains up" in the res. this is the tell tale to see if the piston is returning all the way back enough.