Clean and dry thoroughly as already pointed out then push the wheels across your palm several times both ways to see if the roller wheel moves on the axle up or down or sideways and to see if there are any worn or damaged needles on the axle. If there are problems with the needles and wheels you will feel them scope wrench
What brand and how much use on them?

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)