Buy a reamer (or set of reamers) to open up the hole in the can to an appropriate fit to the shaft - You can’t use a regular drill bit for this, they don’t make round accurately-enough sized holes.
Or pay a machine shop to do it for you.
If you’re only going through the aluminum that works fine but if you also are going through the shaft, I had to drill using carbide endmills because the shaft is case-hardened steel and the bell housing is aluminum and the drill bit would just walk off the shaft into the casing, bend, and then break.
If you do choose to do this make sure to drill the appropriate sized hole before using your reamer otherwise the reamer will not properly do its job.
Mine failed. M4 bolt replacement is temporary. Heading to find some grub screws. Managed to fling the snap ring across the room but overall seems fine now
You can see how enlarged and out of round the pin location indents are on the shaft. These sloppy holes definitely helped managle the bolt and eventually destroy the threads
Need to find someone to index with a pin because this obviously won’t last.
Replacement can is $35. This is pretty frustrating for 30 days in. Hopefully I can salvage this can
Yeah I’m not a fan of the design of these motors one bit. Wasn’t worth the finagling for me anymore—went with Maytechs and haven’t looked back. Fuck these things lol
Hate to break it to you, but Maytech has done the same thing to me.
Unless you pin the fuckers with a roll-pin
Hmm very interesting, yeah the Maytechs I got have a different can/shaft design than your photo. Very interesting though. I wonder what the best design is?
All the current motors will do this. Imagine all the abuse we put through these motors.
They literally just sit all that force through 2 small tiny M3 bolts sometimes set screws (most motors).
If yours hasn’t messed up it’s typically just a matter of time or just luck but the design in itself doesn’t scream reliability 
Ideally, the best option is to add some sort of keyway or something so the rotor is physically attached to the motor shaft rather than sitting on bolts.
Latest batch of motors I did 4 M4 bolts but I’d want to take the pressure off of the bolt holes and put it on the motor shaft/motor can.
Hmm yeah the slot w/ a keyway looks super solid. @b264 had some pics of that right? Wish I had the tools to do a precision mod like that =/
The only downside I had with that is I don’t have enough space to add another 2mm but a similar feature would be ideal. Haven’t decided yet but it has to change.
whatever Maytech does here has held up really well for me
Pretty sure, it’s the exact same setup and luck of the draw. The standard design has worked well but it’s not 100% it could be better. Most of these motors are fine but if we can strive for more reliability, why not.
It didn’t for me, shaft dipped in. Those suck
Pretty sure it’s this 
We get a pretty low failure rate but still if you can entirely prevent it… we should at least try.
same design for SK3s?
Across the board… nobody does anything different.
IMO the best solution is what Hobbyking does with their SK3 and SK8 6374 motors: Use a skirt bearing that supports the other end of the can.
Yeah yeah, I know, that’s a whole can of worms, takes up room for stator/windings, makes it more complicated and difficult to manufacture, yadda yadda.
But it works.
The other thing I can think of is to make the back plate of the can (or at least part of it) out of something stronger than aluminum. A steel piece shaped like this:
tightly press-fit onto the shaft with a key or other rotation-preventing mechanism, and then screwed to the can. That would greatly reduce the tendency for the bore to get wobbled out and loose over time.
The whole design flaw is that of using a small diameter, hardened steel shaft in a shallow, soft aluminum bore. If the bore was deeper than ~1-1.5*the diameter of the shaft, there would be no problem.
If the bore were something with a significantly higher yield strength than 6061(E.G. steel), then there wouldn’t be a problem.
If the shaft were to have a big mushroom end to spread out the pressure, then there wouldn’t be a problem.