hey I'm agreeing with the above, sounds like the problem is mostlikely with in the caliper its self ie, pot being rusted in the bore... if this is the case then bin for the calipers is the better option. but also cheaking that the caliper slides havent rusted up is good too, best thing i reakon is take the calipers apart... inspect condition and then remove all the slides and hit then on the wire wheel... then re grease and put back togeather........JUst FIY if you do take the calipers apart and find theres nothing wrong, i advise getting a seal kit for them anyways, those seals are probaly as old as the car.lol
cheers mate