R8600 Tuning knob

[rocky28965]

I found the tuning knob on my new 8600 stiff to turn.
A similar issue was covered in this thread.
R8600 - Icom R8600 tuning knob "sticky"
With mine the tension adjuster was stuck to the right.
I removed the knob to loosen the 13mm nut but found it to be deformed.
As in, there were only two flat sides on the hex.
The others were sort of rounded off.
I managed to loosen it with a 13mm hex tube socket and free up the adjuster.
So, it is working ok atm.
But I would like to replace the nut for future reference.
Would anyone happen to know the thread size & type?

 

[rocky28965]

I haven't had any luck finding a replacement nut, but instead, have groomed it down to 1/2 inch with a file.
So it is now a snug fit in a 1/2 inch hex socket.
I find finger tight with the socket is spot on.