I know this is a shot in the dark because it's not a massively popular guitar, but does anyone know the size of hex key to use to adjust the truss rod nut of a Godin LG Signature? I've tried both metric and imperial sets, and all of them are just spinning in the hole. Hopefully I haven't stripped it...
I am in exactly the same situation.

I saw your post and was hoping you could help me.
Did you ever find out what tool is required to adjust the truss rod in your Godin LG?

I want to adjust mine & set it up.
But it doesn't look like it accepts a hex wrench?

I've tried all sizes. Was told by Godin that it is 4mm
but don't know what the deal is?

Appreciate any help anyone could give.
I am new to this site.

Thank You,
1.5 yr old thread post but anyway,

Funny, i had this issue yesterday. Couldn't tighten the truss rod, provided key kept spinning. One way i solved it was that i needed to remove the 2,3,4,5 strings(loosen them basically so as to push them at the edge of the nut) reinsert the key from a different direction/angle & turn it.