It was Beatlemania gone mad around Christmas 1964. The Beatles played a residency of seasonal shows at a theatre in West London from Christmas Eve right through the first few weeks of the new year. Paul played his Hofner bass, Ringo thrashed a Ludwig set, George switched between his Rickenbacker 12-string, a Gretsch Country Gent, and a Gretsch Tennessean, and John played his Rickenbacker 325.
Until, that is, John got so caught up in all the excitement that he managed to do some serious damage to his workhorse Rick, dropping it off the Hammersmith Odeon stage.
Startled, John gave the guitar a quick once-over, turning it quickly this way and that. Relieved, he decided it looked alright.
But when he went to play the guitar at the following night’s performance, he found the more he played it, the more it went out of tune. Between songs, he took a closer look, and to his horror he noticed a crack going from the nut around the back of the headstock. Oh dear, he thought. Or words to that effect. What to do? Rose-Morris to the rescue.
Source: How John Lennon Ended Up in an Ad for a Guitar He Only | Reverb News