The only "repair work" I've ever done on power strips is to replace the male plug when the original molded-on pins break off and bend. I use the metal-encased armored type NEMA 5-15 caps.
Once I replaced the switch on one strip at home. It was an old Archer/Radio Shack power strip in a metal case, designed to be repairable.
However, if the cord gets cut, worn or frayed, the entire device goes in the trash. The new piece of cord and strain relief probably cost more than the entire thing would.
We have some "CA" brand strips at work. They came with 6 feet of #14 AWG x 3/type SJT cord.
