Matt,

The factory surface isn't very deep. I think most guys are worried about ruining their expensive hone and so they lap really gingerly at first. Short of dropping and shattering your Norton, or gouging it deeply, it's hard to really ruin these hones. You might have to do some extra lapping to fix it, but since the hones will last for thousands of razors, wasting a little bit of it really isn't going to kill you.

The Norton flattening stone will do a great job of maintaining the surface now. Actually, it would have been fine to take off the factory finish, too. But we didn't know that was the problem.

It's hard for a new honer to tell if the factory finish has been removed, since you wouldn't have any baseline to know how the hone should feel. Spending a little extra time on the initial lapping is good, and feel how the stone's surface changes as you progress.

Josh