OK, the 7VT5 suitcase came in light and dark brown. I'm guessing you have the brown version light this:
http://antique-tv-blazianu.pagespers...orola_7VT5.jpg
Renovated radio has reproduction dark brown knobs (scroll down to 'Motorola VT-71, VT-73 Television Knobs') that would fit, but might not be a perfect color match to your channel knob:
http://www.renovatedradios.com/parts.html
You want the 'C' knob:
http://www.renovatedradios.com/asset...MotorolaTV.jpg