Does the groove cut into any playfield artwork or is it just in the raw wood?

Can you post a picture of this groove? I can't ever remember seeing a ball groove so deep that the ball gets repeatedly stuck in it.

I would think that if the game had so many plays as to wear that deep of a groove, it would probably have an awful amount of playfield wear, as well.

That's no big deal. I wouldn't even call it a groove. Mostly just worn through clearcoat. You must have had that game almost flat for a ball to get caught in it.