Tech: Power Drift sound problem

[matsod]

Hi all!
i have a strange problem with my Sega Power Drift Upright cabinet and
i hope that someone here knows how I can fix this.
When the game is in attract mode, suddenly an engine sound plays, over
and over again, looping forever.
Depending on which gear that is in, the sound shifts. but still loops
forever.

I can play the game, and i think the looping sound disappears (or
maybe it's hidden under all the other sounds playing), but after the
game, when in game over/attract mode again, the people cheering and
some music is stuck in the loop.

I have made three videos so you can see what it's all about, and I
also try to attach the schematic for the sound if that helps out.

https://www.youtube.com/watch?v=IhgPPB0JPJg
https://www.youtube.com/watch?v=u82RqSRaJeU
https://www.youtube.com/watch?v=YmTscJvO-DA

http://i1297.photobucket.com/albums/ag24/ATmatsod/powerdriftljud_zps7e9ab498.jpg?t=1370902685


Thanks a lot in advance/Mattias