I would totally try and fix it myself before shipping it off, even shipping just the arm. But you will want proper strippers for that gauge wire. A new clip would be nice, but you could probably re-use the current one if you're careful. You'll need fine tools- although really the parts are soft enough you could probably get by with some quality tweezers. Mostly what you will want is a flexible vise or clamp to hold the wire while crimping the clip. I'm assuming it crimps, as opposed to being soldered on.
Most likely it failed because when removing the clips to change cartridges someone wasn't careful, the clip pulled off and yanked the wire putting a lot of stress where the wire crimps to the clip. Either that or they did a poor job stripping the wire leaving the wire nicked. Either way you want to be real careful not to repeat that mistake because there's just not a lot of wire there to be doing it over again. Lose even 1cm and you could be looking at a total phono lead replacement. So good luck!
Most likely it failed because when removing the clips to change cartridges someone wasn't careful, the clip pulled off and yanked the wire putting a lot of stress where the wire crimps to the clip. Either that or they did a poor job stripping the wire leaving the wire nicked. Either way you want to be real careful not to repeat that mistake because there's just not a lot of wire there to be doing it over again. Lose even 1cm and you could be looking at a total phono lead replacement. So good luck!