Cup and cone bedding-in

[Trax]

Thanks. The drive-side has not been undone. It's too tight. I removed the non-drive side lock-nut and the insert, and was then able to pull out the entire bearing assembly (both bearing cages - it was the far one (internal/drive-side) which had disintegrated. I replaced the failed cage, packed everything with grease and reassembled. There is absolutely no way that the drive- side insert will spin. It's stuck fast!

Still disconcerted by your narrative.
"if I'd been able to get both sides off" Sorry? Take off the lock nut, spacer and seal/cone from the left side. Pull the axle out 'complete' from the right side (through the freehub (assumed)), taking care to catch all the balls. Access to "both sides".
"cannister" - assume you mean a set of caged balls. These offer no better bearing effect: you're well off with loose balls and dollops of grease. With the axle (complete with one locked on cone and locknut) out you can clean everything and insert new bearings (balls).
"too cautious with the tightening" All that done screw the LH cone on by hand till finger tight and then back off a quarter turn (assume QR). Lock; like you mean it.
"a chance that one of the bearings has failed" - do you mean one of the balls has broken on the RHS (which you have failed to access)?
You will know by spinning the wheel in your hand whether this is the case.
I, like you ("I can't say I understand your point fully"), don't think @Jody 's cunning idea has merit. I just don't see the mechanism for the effect they describe.

 

[Jody]

I, like you ("I can't say I understand your point fully"), don't think @Jody 's cunning idea has merit. I just don't see the mechanism for the effect they describe.

See fossy's reply above and why he uses a spanner on the opposing side.

 

[Ajax Bay]

@fossyant comment sheds no light (for me) on the "why" @Jody . What torque is being applied to the axle (to make it turn) when the LH cone is held steady and the lock nut turned (to lock)? Unless the thread on the axle is fubarred and the lock nut is experiencing 'resistance' from the thread. And even then, so what if the axle rotates: the RH cone and locknut (locked securely together) will rotate. And?

 

[Jody]

I'll tie myself I knots trying to explain this one so get ready for some word soup.

It's just something I've experienced when tensioning cones and messing with lock rings.

Frction or resistance on the lock ring when tightening can spin the axel. Neither the cone or nut has equal friction. The reason they lock is because they are being forced together by the thread using opposing rotation.

If the axel spins clockwise with the lock ring (because it has more friction) whilst the cone remains stationary (in relation to the hub) it's effectively loosening the axel tension.

 

[Ajax Bay]

Understood. I suppose I always just go finger tight, both cone (back off a quarter) and then the locknut (by hand/finger tight), and then it'd be max half a turn to lock. If the axle has turned (as described during the locking process) then the adjustment will be too loose for the QR to take up. Reiteration: have another go without the quarter turn back on the cone. Repeat till mummy bear.
But if the OP has this 'right' after the QR is secured and before riding, with the LH locknut and cone securely locked together . . . .