I think the right teacher can teach you how to figure almost anything. You don't say where you are on your musical journey, but knowing some basic theory will help. Ear training and some loop and slow down software will help. You probably already listen to quite a bit of Phil Lesh, but you'll probably learn to listen even more carefully. I was a Dead Head at one point, and I understand the appeal. Phil Lesh certainly has his own style.
Broaden your search to find teacher who can teach you how to figure out parts on your own, but also consider the other skills a teacher can build. Left and right hand technique. Sight reading standard notation. Ear training. Improvisation. Applied theory. Instrument set up.