Here's info about the bass from the Hofner website:
Here is a short history of this bass and what happened:
In the spring of 1961, Paul McCartney, of the little known Liverpool r'n'r band The Beatles, became their full time bass player. Being left-handed, he custom ordered his first bass, a Hofner 500/1, through the Steinway shop in Hamburg, Germany during a two month residency at the Top Ten Club. Back in England, he played all their Cavern Club gigs with his new bass, as seen on the BBC’s first Beatle's footage. Hence its nickname, the Cavern Bass.
This instrument was solidly used by McCartney until October 1963 when he received a new Hofner bass from Selmer, the UK importer.
It was played on some iconic Beatles recordings including their very first studio outing in June 1961 in Hamburg, their first single Love Me Do in 1962 and their first two albums, Please Please Me and With The Beatles in 1963. It's the one you hear on "She Loves You, "Twist and Shout", it was played in Hamburg, at The Cavern Club, at Abbey Road, isn't that enough alone to get this bass back! I know, because I talked with him about it, that Paul would be so happy, thrilled if this bass could get back to him.
McCartney kept his first violin bass until it went missing, using it as a back-up during the Beatles' world tours and playing it again in the Revolution promo video and during the filming of Let It Be. He cherished his first bass as stated in 1966 Beat Instrumental interview: "I have had a Hofner ever since I started. I've got 3 models but the ancient one is still my favorite. It has seen so much work that some of it is held with sellotape!".
The bass was in need of repairs and so it was sent to a firm in London, early in 1964, who carried these out.
They resprayed the bass a darker 3 part sunburst and fitted new knobs. Most significantly they custom made an unusual single pickup frame to hold both pickups. It was very distinctive, no other 500/1 bass looks like this.
