No it's not a big deal, your better off like i said getting a hammer and a screw driver and just slowly working that lock nut out then remove the bearing and just order one from your local yamaha dealer probably cost you 15-20 for the bearing and another 8-10 for that lock nut.
I know it's just a steering stem bearing but i always replace em' if i have any doubt. Especially if it has powdercoat all on it...lol