brake fluid shoudl be changed annually, also incorrect fluid could cause the brakes to fail. you shoudl first have the lines bled and filled with teh correct fluid (from a freshly opened can).
next if the pads are good, have a look at the disk/drum. if the contact suface is flat you can eliminate this as a problem. however if your pads are worn have them replaced. if hte disc/drums are scratched/pitted use ONLY sandpaper to haveb the surface slightly smoothed. if you feel the damage is enough to justify "tooling" then it's better you swap out the disk/drum. make sure you take the time to "bed them in" after fitting any new brake components.
if all else fails, have the seals checked in the master cylinder (if possible) otherwise if it is not forming the correct pressure then replace it.
maybe he's got some other "shawks"