[aumoore]

Are the lines running from the master cylinder to the front brakes the same length on both sides? If not this will cause a pull by applying less pressure to the side with the longer brake line. This is a old race car trick that I read about somewhere. The lines have to be the same length and if I remember correctly a 1'-0" longer line can affect brake bias.

Could be a sticking piston in the brake caliper as well. Make sure you do not have the old phenolic(very hard plastic) that was used about 10years ago. They are nortorious for getting egg shaped and sticking in the bores.