Hi Swegmang, yes it's possible to repair it but it would be a lot easier if you repaired it right as soon as it became an open surface instead of a closed solid. Don't just continue to do more booleans on the object that isn't a solid because you'll keep on opening more and more holes each of which will need to be filled in order to repair it.
There is a tutorial on object repair techniques here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=446.17
To begin with repairing it, first use the select naked edges script that I posted above, it will show you the areas that are open.
First there is a big hole in the front part:
To repair that, you'll need to re-create the cutting line, you do that by copying these curves down (hold down Ctrl and drag on them) and flattening them (switch to the front view and use the edit frame to do a "flat snap"
http://moi3d.com/forum/index.php?webtag=MOI&msg=3378.4 ). Also replace any series of multiple lines that are colinear with one single line:
Now that the original 2D planar cutting curve has been restored you can now extrude it up like this:
Now you need to cut the new extrusion with the edges making up the hole, these are the cutting objects:
This will cut the extrusion into 3 pieces, select these outer ones as the pieces to discard:
That will leave you with this trimmed surface:
That's the piece needed to repair the front, select it and the main object and use Edit > Join to glue them together and seal off that hole.
Then there's another area to fix on the opposite side, I'll post about that one next.
- Michael