i hav the mk3 manual, if u hav an mk2 machine and the jamma from an orgional mk2 machine, the run button connections should already be there, just try one of the unused connections, after to find it than all u need to do is splice a ground off one of the other buttons. If u still hav probs getting it to work, pm me and ill photo copy the wiring diagram. but when u did mine the wire was there just unused from mk2.

Yes there is a unnused connector there, and a label for "Player4" is on that.

But I need of course some wiring for the connetion of the 2 Run Buttons.
Can I use some standart isolated wire for that?

yes, any type will work

Another question, whats a good price for a UMK3 Board?

I dont know how rare it is, so whats the average price for such a board?

MK4 is always very expensively.
But whats with UMK3.

There's a few UMK3's on eBay going for $20 with a few days left right now.

Matt