The ball drains and nothing happens doesnt give the bonuss or anything. 

I have precisely the same problem on one of my machines - in my case it is dodgy 9 pin connectors where the switch matrix plugs onto the driver board. I've come to the conclusion the only way I'm going to obtain reliability is to completely repin every connector.  Pretty easy to do, but not a lot of fun and time consuming.  BTW the ones in mine are IDC connectors, which may be worse than standard ones.

Will have it sorted before the weekend is over

I admire your optimism  - At best I'd put it that you may have moved on to the next problem