01 740i - Radio volume knob

2001 740i. I just upgraded my old radio head with the newer widescren display. I noticed that the bottomm left radio volume knob is slightly loose. Does any one know how to tighten this? Any links that explain how to do this? Any repair shops? Thanks for the help. Tom

not to high jack the thread,Id like to buy a radio knob for my 2001 bmw 740i. mine is a bit worn out.

I do not have the wide screen, but the older nav system

any links where to buy one?