Grab when launching

[m.brouillette@comcast.net]

Guys,
         I think I know what it is, but wanted to ask the experts.  I have a 59 
BT7 that runs like a champ.  On occasion I will come to a complete stop at a 
light, and when I try to take off, something is grabbing and won't let me go, 
like the brake is still on.  It feels like a grab and if I bump up the RPMs and 
take off it will go away.  This doesn't happen every time which makes it 
frustrating...
Any Ideas?
Mike B
59 BT7