They may be two of the most influential notes in funk-rock history: the soaring, plaintive start to guitarist Eddie Hazel’s legendary solo in Funkadelic’s “Maggot Brain.” The song, an audacious, emotive 10-minute-long bluesy ballad kicked off by a brief, eccentric poem from leader George Clinton, is centered on Hazel’s expansive fretwork. Clinton pulls the bass guitar and drums mostly out …