I fitted a Cane Creek headset when the Mojo was new and it has been great. Until now.
But four years of mud have eventually got through the shields and it needs new bearings. I have removed the fork when cleaning the bike and lifted the shields carefully and checked them but up until now they have been in great condition. Recently the smoothness started to decay and graunchiness arrived. A quick search for the correct bearings and a package arrived with the postman.
I would suggest removing the brakes and shifters etc. before removing the bars and stem but if you are really careful everything can be left attached and just the stem detached. Got to be careful though. So with the bike in a workshop stand, the stem is removed and the top bearing and bits all removed. (spacers and locking collars and washers but these vary by bike and setup). The detached fork lowered slowly, the bottom bearing lifts off.
Clean everything, put the bottom bearing on the correct way up, some grease, fit fork, new top bearing, all the little bits, stem and bars, straighten and tighten. Twenty minutes or less depending upon the bike and an easy job really. Different headsets may require removing pressed cups, re-facing headtube and even removing bits from forks so check yours before you start but the internet will have your exact set up somewhere.
To check your own headset turn up on a ride and ask me, or check the internet as usual.