The board goes where the female power plug normally goes in the mpu, and has that plug go into it. So it kind of stuck between the board and the plug.
The problem with resets is that the game's 5 volts are pulled too low, due to strain caused by the higher voltage solenoids. They only cause the voltage to drop by about .2v. The thing is that some chips start acting weird at that low a voltage. There's a special circuit put in, called a watchdog circuit, that will say "STOP! Reset this game!" if the voltage gets below a certain point. And that point happens to be 4.85 volts.
So there's two versions of the board, the normal and the deluxe. The normal version takes the 12 volts, which doesn't drop as low when strained, and converts it into 5 volts. This means all of the mpu board, which includes the watchdog circuit, always has a strong 5 volts. So it stops resetting.
The deluxe version does everything the normal version does, but it will also light up little lights to tell you if it was needed or not. This can help you diagnose what's causing the voltage drop, or just let you know the health of the 5v system.
The alternative to these boards is rebuilding the 5v path of your driver board. The voltage is dropping low because the parts are old and drifting outside of the normal operational limits. It can be a pain in the butt, though, and may not solve your problems.