That's good advise! Always have an up level adjuster and O-rings on your truck. If you can't see through the hole just replace it, don't try to clean it. And if you can turn the adjuster by hand, replace the O-rings because it will turn on its own.
They are great valves though. The 20 fpm steps in the down high speed adjustment is frustrating when setting them up but from a maintenance standpoint, the only real downside is that you can't just adjust the down stop a little to hit the floor better without spending some time with the other down adjustments.
