Look in your schematic and test the voltage on the board with the game off. If you're not getting full battery power on the board it's likely corrosion has damaged some of the traces and you'll need to remedy the damage and arrest any further corrosion.

Remote battery holder installed? Photos of the board?

You might pull the battery holder off and see if you have board damage below it.

LTG : )

Get help if you've never done board work. Unsoldering involved.

LTG : )

Post your location here and in your profile - maybe someone local can help you out??

Post a picture of the board. That will help as well.

the MPU board. The biggest board in the backbox.

Post a picture of the board so that we can have a look over. Sometimes alkaline damage is not hard to spot.
I've been upgrading boards to NVRAM so no longer would batteries be needed.

It's more likely the corrosion is underneath the holder and has damaged the board. Many times this is not a big deal and can be easily fixed by cleaning and installing a remote battery holder (easy) or upgrading to NVRAM (less easy but a better solution)

I suggest you remove the battery holder from the board, take good photos of that area (front and back if possible) and post them so you can get eyes on that section that know what they're looking for.

This section of the pinwiki covers repairing alkaline damage on games similar to yours.
http://www.pinwiki.com/wiki/index.php?title=Williams_System_9_-_11#Repairing_Alkaline_Corrosion

You're getting the message that shows up when battery connection is lost. The MOST LIKELY cause (since you have new batteries) is corrosion but without photos that's just a guess.

I'm in central Florida
And could help but pm me
And we can go from there

Yes.

That crap gets everywhere. you can't be to careful. catch it early is way cheaper than buying a whole new board.

LTG : )

You are kidding yourself if you don't think there is damage under that battery holder.

Crap around the edges, clip corroded. Crap around the solder points. Crap leeched into the fiberboard.

John Wart Jr or Chris Hibler post here on Pinside, both can help you if you don't have anyone near you.

LTG : )

Should be just the 6 spots you can see, 2 for each battery. Cut it off and post more pics.

Yeah
Get that holder off there and start cleaning it up before it causes more damage. Pull the board out and unsolder the holder which is 6 spots.
Out of curiosity did you just buy this machine ??

Where are u at in central Florida ??
I would be more then happy to give you a hand with this

You can do that but if you don't fix the acid damage that's already there it's only a matter of time before it destroys the board.

I live about an hour from you
If you need a hand with it I would be more then happy to help
You will need to pull the board anyways

The original holder is trash. No use in putting on another holder, even a remote one. Seek gameover1173 help since he said he is available to you to get the board repaired properly and have NVRAM installed so no batteries are no longer needed. This board is too delicate to even try to practice cleaning up as some actual parts need to be replaced. Defiantly looks like this board can be fixed up nicely so a new or replacement used one should not be needed.

i sent you a pm back with some info

That board has a lot of corrosion damage!!!

Definitely take the offer of help repairing the board. Alkaline is like rust, it'll leech itself through that board til there's not enough left to repair.

To repair that properly, you're looking at a few hours of work. You can't just 'rinse' it with vinegar and say done - the board has to be sanded down to bare copper anywhere the solder mask or copper traces are discolored, sealed, and every component the alkaline touched must be replaced. Otherwise, you're just wasting time/money.