Yes, that would be the problem. In all likelihood, that joint needs repairing/replacing. Common repairs often fail (seems to be the consensus from this thread), and since you’re now feeling a humming, that implies there’s some damage to the joint itself. Your best bet, at this point, is to replace the axle with a new or rebuilt unit. Again, the consensus here is that rebuilt shafts don’t work all that well, nor last that long.
I’m not sure who it was (Caddyman? Keith? Someone else?) who had a link for replacement shafts that aren’t much more than rebuilds, but seem to be much more reliable. Hopefully they’ll pop on soon and post the link for you.
Good luck,
Chase