Ok, so there is a difference in hole size? Perhaps you can fill up the gap with Polymorph?
Polymorph is a biodegradable plastic with nylon-like strength and flexibility that becomes completely malluable at 60 degrees (centigrade, of course
).
You can just heat the polymorph granulate up in hot water, take it out, smear some of it over the driveshaft and mount the wheel on (make sure it's centered nicely).
When it's cooled off, take the wheel off and possibly remove some excess material that ended up between the hex and wheel. Job done!
This is all theory though... Polymorph is great stuff but I've never tried to fill small gaps with it. It might just be worth a shot though. If it doesn't work all it takes is hot water to get it off again anyway
