I swapped the board on the nav slot
What board on the nav slot? If your nav drive spits the disc out and cleaning the lens hasn't worked, you then need to change the laser assembly.
I might try and put everything back onto the original unit as one last attempt but I'm not sure what to do currently especially seen as the radio and CDC work fine and it's very very rarely I use the Nav it's just nice to know it's there sort of thing...
Ok, I'm truly lost now! (Not hard for me!), I presume you have two head units and have been swapping bits around to try and make one good one? So if the Radio and CDC work fine then just the Nav drive needs repairing? Do you have a spare Nav drive from the other unit and was it ok apart from spitting the discs? ...and has it been dismantled?
So hence why I'm on the lookout for a CID ideally or failing that a GID NCDC 2013. I'm not in a rush or anything just thought it's a good opportunity to upgrade to a larger colour display
Only used an NCDC with a GID and few times, but the CID makes it a much better tool in my opinion, if you can put up with no postcodes and 2011 maps then it's still a good bit kit.