Here is the owner's manual for the Ms PacMan/Galaga machine.
There is a "test" button behind the coin door. When you press it, a menu comes up on the screen:
1 MS. PACMAN ADJUSTS
2 GALAGA ADJUSTS
3 GENERAL ADJUSTS
4 SHOW AUDITS
5 SWITCH TESTS
6 MONITOR ALIGNMENT
7 FACTORY DEFAULTS
8 EXIT
You use the joystick to go through the menu, and hit any button to make a selection.
Select "1 MS. PACMAN ADJUSTS". That will lead to a second menu page:
MS. PACMAN PER GAME …….……………….1,2,3, or 5
BONUS MS. PACMAN ………….………………..NONE, 10K, 15K, 20K
DIFFICULTY ………. …………………………….NORMAL, HARD
SPEED………………………………………………NORMAL, FAST
DEFAULT SETTINGS…………………………….FACTORY DEFAULTS: 3-PACMAN, 10K BONUS NORMAL, NORMAL
EXIT
Select SPEED NORMAL. And then EXIT through the menus. Good to go.