The opening instrumental for -Seventeen Seconds- is simply:
Riff A:
A5 Bb Gm A5
E -5-------|-6------|--3-------|--5------|| B -5-------|-6------|-(3)------|--5------|| G -x-----5-|-7------|--3---6-3-|--x------|| D -7-------|-8------|--5-------|-(7)-----|| A -7---7---|-8------|--5-------|--7------|| E -5-------|-6------|--3-------|--5------||
(The number in the parenthesis is the note that is accented by the piano Playing)
Riff B:
Fmaj7 F5
E -0------|-------|| B -1------|-------|| G -2------|-------|| D -3------|-3-----|| A -3------|-3-----|| E -1------|-1-----||