There are several reasons you may want to run your Gauntlet I without a slapstic. Say you broke your slapstic because you ran over it with the forklift out in the garage. Or say you wanted to try a multi game hack.
You really have three options in this situation:
* Scrounge the net looking for cursed part 137412-104.
Don't even bother...it would be easier and cheaper just to buy a whole Gauntlet board!
* Reverse engineer the slapstic, build a daughterboard for it, and hope it works.
Some people are working on this (myself included). It probably won't be long now. However, hacking together a replacement is probably not for most people because it will likely involve burning your own PAL(s) and building some sort of PAL-->slapstic adaptor.
* Run your Gauntlet without the slapstic.
Because Jay 'Whip' Grizzard (firstname.lastname@example.org) and I are insane, we have figured out how to fix this problem. You need to do two things, and they are quite simple. The first is that you need to replace the ROM at location 10A (136037-205, not the -105 part!) with this new, carefully handcrafted replacement. It is a 27128.
The next step involves some hardware. Pull out the slapstic which you don't have. Then, get a 20 pin machined socket and solder these two wires (on the top, silly): From pin 4 to pin 10; then from pin 5 to pin 9. Plug this socket into the slapstic socket. If you don't have spare sockets laying around then you could (I suppose) just jam the wires into the socket on the board. Please make sure that you insert the socket correctly, not backwards, or you will really be sorry.
Now you can turn on the machine. It will work, and you can just ignore the ROM checksum error if you see it. This is because one of the ROMs has been modified.