Luckily, it's a Pac board... probably the most well-documented arcade board in existence. If you need it back by the Holidays, it shouldn't be an issue. There are several people on here that repair boards, and some of them "specialize" in Pacs. You could probably work something out with them if you're not comfortable replacing the chip yourself.
With something like that that seems like it would be an easy fix, they could probably get it in one day, and have it back in the mail to you the next.
As far as what 3N p5 high means, it just means that the IC at the location 3N of the board (a 74LS74 chip) has pin 5 stuck high.
Pretty easy to replace if that's indeed the issue (easily checked with a logic probe). To avoid doing any hard desoldering, it's just a matter of cutting off all the legs of the chip, heating and removing them 1 by 1 (easier than it sounds), clearing the holes, putting in a socket, and slapping a new 74LS74 in there. ... again, that's if that's the actual problem. A quick peek with the logic probe would confirm what is or isn't wrong with that chip.