The Pixies and rock's revolving doors

At this time last year, the Pixies lineup looked like it had since the quartet of Boston-area musicians first got together in 1986, with Black Francis (or Frank Black) on lead vocals, Joey Santiago on guitar, Dave Lovering on drums and Kim Deal on bass. Twelve months later, the band is on its third bassist (and first not named Kim): Paz Lenchantin, ex-Zwan member.

But the Pixies aren’t the only band that has survived personnel changes. In fact, some bands are particularly tough on certain instruments, with a constantly-changing cast of characters. Here are some of the music industry’s most difficult gigs, ones with the least job security. Land one of these assignments? Keep your resume up-to-date.