Hohner B2 truss rod hex size?

[Leyland Ska]

Trying hex wrenches (good quality ones), 5mm fits in the socket but is loose. 5.5mm and 7/32" don't fit.

Could it be 13/64"?

I can't reach a Vernier caliper into it, or get a decent imprint of it with Blu-Tac

The hex socket looks in good shape, not rounded.

[tauzero]

Mine is a nice snug 4mm. Go smaller.

[Leyland Ska]

Hm. A 5mm hex is loose, sloppy fit in the socket. A 4mm will probably not even touch the sides. I definitely don't need to go smaller.

 

Wondering if Hohner have ever used 13/64" or anything else exotic.

[tauzero]

Have you tried putting a 4mm in there? There's an initial round hollow bit (which a 5mm would go into) followed by the 4mm bit (which a 5mm wouldn't). Everybody in the civilised world uses 4mm. Hohner use 4mm on the B2.