It really is simple, although can be time consuming. OP wants to spend a few hundred on a problem that will require an hour of work...and the cost of some grease.

FWIW, I've come to enjoy servicing loose ball hubs, and once a year won't kill anyone.

I'm curious why the stock ones come out of adjustment, though -- are people not tightening the locknuts against the cones enough?

Just like why so many factory built wheels have poor spoke tension, they are sold to retailers in hopes that they will be professionally serviced. So not only does this guy have tight grindy hubs, his rim probably goes out of true every other day.

Makes sense, but I'd think they should stay in adjustment once done right.

Not if the hubs, bearings and hardware are shoddy to begin with.

Can anyone here service my loose balls?

can you not read?

ehem:

+1 I had a set of loose ball hubs that would need adjustment every two weeks, even after a professional repacking.

i'll show u some balls...

Where did the OP go?

to get his balls serviced.