It's obvious the existing seals are flawed, since most of them are broken and the rest are weakening. It seems logical that he would have to take down the old seals before putting in new ones.

When the AS first drilled into the bore in the AoL, they drilled through an apparently new surface, not through an existing patch. So according to Herid Fel, that means that somewhere along the wheel's turning, the bore has to be healed back to be literally as good as new.