Step one, dig through the trash and look for one of these:
Next, grind off those itty bitty little tabs and give the shaft on the other end a rap against something hard. Everything should come apart with no problemos. Pry out the two magnet clips and then give the open end another rap on something nhard and the magnets will most often just pop out as well. Now that you're done with all that...throw everything but the magnets, clips and can away (*unless you wanna try rewinding the arm).
Now you can do some scratching to lay stuff out. I scribe a line on both flats at .750", and do some other marks for guides. When I cut the length, I stay away from the lines and then start truing everything up by playing the open can end against the flat of a large grinding disk.
Once I get it so I have the same length on both flats (*within a thousandth or so) and the end is smooth/shiny on all four sides (both flats and both radii), indicating the grinding disc was making full contact, I call it done. In this case, I also opened up the two can holes and squared off the corners for a little better breathing. Last, the two "magnet stops" that are formed into the rear end of the can get ground out. They now become axle-clearance notches as well as allowing for more flexibility installing the magnets as far as "fore and aft" positioning.
Last, using an end bell and a goofy alignment "tool" made from a junk shaft and some tubing, a new tight bushing gets soldered-in. We're getting close to having an actual setup.
Of course, the inside gets cleaned-up after soldering-in the bushing, also making sure that any old magnet glue gets removed. The rim inside the open end of the can gets a slight "bevel" to ease installing the end bell. Warning, blurry photo alert!
One of the last pieces of the puzzle is fitting an end bell. While the original motor is called an "fk" size, end bells for motors like the PS "Euro" and Hawk (*which are also called "fk" size), will not fit here. You need to "shave down" both curved faces of the end bell, but not the top and bottom flats. I use a spiral cutter in the grinder that doesn't have an "end cutting" profile. That way, you can use the very slight "lip" on these end bells to play the tool tip against (*carefully/lightly) and shave down the curves. Once the end bell fits snugly, I give the two curves a light sanding to smooth things out and also put a slight bevel on the bottom of the end bell to also help ease installing it. This little bit of work on the end bell is a lot easier than turning down a C can end bell (*today, we're lucky to have ready-to-go end bells), and doesn't require a lathe and fixture gizmos.
A final check for end bell/can bushing alignment, and the only chore left is to drill the can for end bell mounting/securing holes. After that, the setup is basically "there", at least there-enough to build an arm and lock-in the magnet position.