The re-tip with original cantilever is not possible. None of re-tippers have the square shank cantilever if we are talking about early Carat with 2mm short cantilever None of the re-tippers can make square extension to fit new cantilever. The cartridge most likely is as good as the door stopper. Abandon this idea. Also Average re-tip with descent cantilever/stylus at SoundSmith if $400. The cartridge worth $300-$400. You can get plenty on internet. Also if some re-tippers claim they can glue the stylus to existing cantilever- it is impossible to do correct angle and alignment without computer laser alignment. if you agree on conical stylus- then it is possible, but your Karat will sound like 60s Shure.
If looking for budger cartridge new or used- check viraUSA website
If looking for budger cartridge new or used- check viraUSA website