1992 Rude E150GLENC

Think I found it, let me know what you think. When I pump up the ball I have a trickle of gas on the bottom carb on the starboard side where it meets the manifold. Would this just mean I need a new manifold seal or could there potentially be a larger more costly problem? If it is just a manifold seal, what's the time involved (by a professional) to change one? I'm supposed to be leaving Wed for a tx next weekend. Go figure Monday is a holiday, hope it doesn't set me back Thanks for your help