[Beefy 1965]

Here is another option:

Incorrect result Gamball -4
Incorrect result Bonus -2
Incorrect result -1
Correct result +1
Correct result Bonus +2
Correct result Gamball +4
Correct score +2
Correct score Bonus +4
Correct score Gamball +8

That would make it still worth playing the Gamball and not penalize those for getting other score right.

Yeah can see what you did there
More or less halved the winning balls,
Could work that