by Ken Scott. The song was difficult to learn due to its time signature changes. During the first 18 takes on 7 August, the band focused only on the introduction, before going on to tape a further 27 takes that night. On 8 August, they first attended to a technical problem on the recording of their forthcoming single, "Hey Jude", and then resumed work on "Not Guilty". The group recorded a total of 101 takes over the two sessions, although only 21 of these attempts were complete performances, before settling on take 99 as a satisfactory basic track. Initial takes included keyboard accompaniment from an electric piano, but this was replaced by a harpsichord for the 8 August session. The instruments used on the basic track were therefore electric guitar, harpsichord, bass and drums. Although author Ian MacDonald says Harrison or Lennon played the harpsichord part, Everett credits Lennon, who also played the instrument on "All You Need Is Love" the previous year. The recording marked the first time that Harrison used his Gibson Les Paul guitar known as "Lucy", which was a gift from his friend Eric Clapton. Overdubs The band recorded overdubs onto take 99 on 9 August, with Starr adding further drums and McCartney augmenting his bass part. Much of the six-and-a-half-hour session was dedicated to Harrison's lead guitar part; for this, he chose to play in the control room while his amplifier was recorded in an echo chamber. On 12 August, Harrison overdubbed his lead vocal, trying different areas of the studio in an effort to achieve the sound he was after. He again settled on the control room with, in Scott's description, "everything coming back through the speakers to give it more of a live theater-type feel or club feel". Lennon and McCartney experimented with harmony vocals on some parts of the song, but Harrison was unsatisfied. Scott told journalist Marshall Terrill in 2012 that the recording was problematic because "George wasn't feeling it. It was his song and he wasn't feeling it. He could not get a vocal that he was happy with. He couldn't get even into sort of the mood of singing it, that's why we tried different ways of him singing it …" Harrison then spent more time recording guitar at live performance levels. A mono mix, titled RM1, of the completed track was carried out that same day. In the