Originally Posted by aixaix

One trick I've heard of but never tried is to assemble the pedals with valve grinding compound instead of grease, then spin the axle with a drill. This should hone the bearing surfaces. It will destroy the balls, but ball bearings are cheap. If I were you, I'd try it, using a medium grit first, cleaning it out, then using a fine grit.

Replacing the worn axles & cones is better than trying to save them, but may be expensive. Machining the bodies to install removable cups is going to cost a mint. Installing sealed bearings means re-sizing the housings and axles. I would be reluctant to do this. It amounts to re-engineering a highly stressed and critical component, which can fail in many interesting ways!