Did you loosen the clamp bolts before removing the preload cap? If you didn't, that would account for having a tough time getting the preload cap off. There are replacement bearings available at
http://www.enduroforkseals.com/id227.html for $15 if you want to go that route. Also, make sure the spindle is well greased where it contacts the bearings as this can be a source for noise.