Come back again this morning to try and fix what I've broken.
Managed to round off bolts and bend the linkages cause I left the box resting on them overnight. And still haven't found the magnet so I reckon that's the end of this conversion.
Didn't think it would be anywhere near this difficult and it's gotta be out the workshop today so will be getting dragged back to my yard and then broken for spares in the summer.