Please excuse my ignorance, but I took the leap into home maintenance this weekend figuring I would finally make the effort to do that annual repacking of headsets and BB's that are so recommended.

Q2: on removing the BB our of my circa 1994 Spec. Allez (probably 105 but the actual part number was partially obliterated and I've put it back together again now anyway), I was surprised it seemed to be a sealed unit with no obvious way to get at the bearings.

are such sealed units not supposed to need repacking (one book suggests it does) or maintenance?

otherwise, how often should one replace a cartridge BB?

(if it helps, I can remove it and take a picture.)