True-bypass mod for George Dennis GD30 wah?

[skrunk]

a dude has asked me if I could do a true-bypass mod for his George Dennis GD30 wah (circa 1994).
I've no experience with modding wahs and I'm wondering if it might be easy or tricky to do.

would it be a case of just changing a switch?
he doesn't live nearby, so he'd have to post it to me, and I wouldn't mind having a look at it first.
obviously I don't want to ruin the guys pedal by botching it!
anyone ever done this particular mod?