I love this game! Glwts

Not trying to be "price police" on this one but the issue you have is you are trying to get $500 out of a $300 machine and that is why it is still for sale. Sadly most of these earlier Gottlieb SS machines are worth more in parts than they are worth as project or even semi working machines.

Working with playfield wear and other minor issues it might be a $500 machine or not working but exceptionally nice cosmetically it might be a $500 machine but a non working players quality machine is worth around $300 to $350 at best. Typically I like to grab them under $250 when I am actually looking for them

Well, he's not wrong. It's been listed for almost half a year.

Worn, non-working system 1 games don't go for a whole lot, unless it's one of the few desirable titles (such as Genie, Hulk, or Asteroid Annie).

I struggled to get $300 for a non-working Sinbad with a beautiful playfield with flat inserts.

If you really want to move it, you're probably going to have to either reduce the price significantly or get it working. Post photos of the boards and displays--that should help too.

The ni-wumpf board is probably going to be the least expensive MPU option (although if you need to by 2 or more, the pascal MPU-only board works out to be slightly cheaper). Sometimes you can get the original MPU going. The problem areas are generally the battery damage, the u5 spider chip getting shorted, and/or a bad AMI RAM chip. Two of those things are generally fixable.

Not trying to give you a hard time just trying to make you aware that after having something listed for several months and having it still for sale it might be time to realize your price point is way too high if you honestly expect to sell that item. Fully working a Count-Down in that condition might be a $600 to $650 machine on a good day. So you basically have a couple choices - first do like ForceFlow said & fix it before you sell it, second try somewhere like eBay and hope you hook someone who doesn't know any better, or lastly cut you price.

If you don't care how long you wait you might get lucky and find someone to buy it I just doubt that will happen here on Pinside from my experience with buyers here.

In any event best of luck to you and Happy New Year!