>fuck knows why you would put any off set on a drag knife but this has a 4mm one.

Fairly standard ain't it..? But yeah, it's a ball-ache when you want to get going and something unexpected trips you up. Fair few threads around on compensation, you might try starting here:

http://www.cambam.co.uk/forum/index.php?topic=3628.0

Does look like you're in for a bit of a faff, though..!

Good luck.

Wal.