How to replace leg knob on Benbo Trekker tripod.

[girlie]

I got the replacement leg knob for my Benbo tripod, it came with no instructions, and I can't find any on Paterson's website, and haven't been able to find any directions by doing a Google search. I can't figure out how to do it by looking at it, either.
Can someone here tell me how to do this?
Thanks in advance.

 

[SMBooth]

is it the classic leg knob like this
http://www.patersonphotographic.com...5&licenseKey=38766b5aba7056dc12ebc00c6db476bc
it looks like it just unscrews if it is.