Fix slot machine so you don't win on average.

If my math is right, you got on average (in 10.000.000 plays):
perl -e 'print 2000000*0+400000*40+152000*190+7448*4990-7440552*10 ."\n"'
7640000 credits, or 0.76 credits per play.

Changed it to:
perl -e 'print 2000000*0+400000*40+152000*190+7448*2990-7440552*10 ."\n"'
-7256000
or -0.7 credits per play.