For the Super Record pedals, I too had issues with the tiny bearings.

my solution was a 9/16” bore into a dense hardwood block, big enough to be stable on the bench or smaller that allowed to be clamped into a vise. One really needs a drill press as one wants a secure fit. Hand held drilling won’t cut it.

inserting the spindle end bearings up allows loading the bearing balls effectively and using tweezers to manipulate. The shallow races really make this job more of a challenge that it should be. Campagnolo could have used the typical bearing diameter on the outboard end.

load the cone and finish adjustment.