OK, changed it to suit one of the score cards,55,00...69,000...77,000...
It knocks at each score no drama.but when you go on to max bonus 5000 it does the big buzz sound credit wheel and knocker locked on.
I have no clue but it must be a switch or relay stuck on when 5000 bonus is scored that freaks out the knocker and credit wheel,because it behaves perfect when it knocks at 55,69,77,000 and the credit wheel advances a number per game won.
I just don't know where to look for bad switch !!
THANKS EVERY ONE HELPING  would like to solve it though