replacement 1/4"-3/8" reversible screw and locking wheel for Gitzo G557 boom pole?

[Josh Bass]

So I got a Gitzo G557 boom pole (for free, which will explain my upcoming question).
Essentially the same as this (this is what comes up when I google search this pole)
http://www.bhphotovideo.com/c/product/609126-REG/Gitzo_GB1340_GB1340_Series_1.html
(click the picture to see a nice closeup of the head and screw)

Wondering if there is a way to get a replacement for the screw that goes in the end. . .it both screws into the end of the pole AND is screwed onto by a shock mount. There is also some kind of "locking wheel". . .I guess to secure everything.

The person who gave me the boom had a. . .thumbscrew? (I'm so not a hardware guy) holding it all together right now. It's a little loose and I'd like to get something more secure.

This appears to be an older model that nobody sells anymore. I already contacted gitzo and asked 'em the same thing, but wondering if there's some easy off-the-shelf solution from a hardware store. . .a double ended screw or something that would work.

Thanks.

[Josh Bass]

ah crap. Found it. After I posted this, of course. Still worth seeing if something at the hardware store can save me $16 and shipping.

Ok, maybe not. The stuff I found say it's meant for Gitzo tripods, not booms.