Quoted from LesManley:

I think it was cut on a line with a razor blade when it started cracking. I've seen that a lot. That fire button is the wrong color too. Doubtful they would have replaced that on a home use only game.

Quoted from LTG:

That is highly unlikely. Distributors back then wouldn't screw ops over by selling direct to a non operator. Especially before they hit the streets. Arcades or other locations.
LTG : )

Quoted from meSz:

Agree with this statement! I seen a post by a new Pinsider claiming their machine was HUO but first thing I noticed was the front of the cab had the holes for a lock bar. I asked the seller about it being listed as HUO and their reply was .... "I wasn't sure what condition to list it as and I wasn't sure what HUO meant......"