The spacer on the lockring isn't normally separate. It's a thin wavy captive washer that doesn't provide a flat surface to get the ring perpendicular to the axle.
Two tricks:
- Use the lockring tool to install it, especially if it has the lead pin that sits in the axle.
- Turn the lockring backwards until you feel a bump as the start of the male thread passes over the start of the female thread. Then turn it forward so that they engage.
Thanks for the tips...but still no joy. The lockring does has the captive wavy washer...I pushed it down so hopefully it's not interfering.
And my lockring tool does have a lead pin. I tried carefully turning backwards, felt the "bump" then started turning forwards. It seems to engage, but only goes about 1/8 turn before significant resistance is felt. Looking at the lockring from the side, it appears perfectly parallel to the cogs (i.e., not cross-threaded). It may just need some additional torque to get it going, but I'm afraid to do that for fear of screwing up the hub body and/or lockring threads.
Hopefully, the pro wrench will be able to get it installed OK.