Slider uses a large bearing assembly in the steering head much like those found on a bicycle, except that instead of just handlebars, there is an additional 30+ inches of steering tube that leverages against the stem assembly, which may work loose over time.

Use a strap wrench or large adjustable (channel lock) pliers to tighten (clockwise) the knurled steering head adjusting collar (found below the handle pole release clamp) until the steering begins to feel stiff or notchy then back it off ever so slightly til smooth; while holding the collar from moving tighten the locking nut down with a large crescent (adjustable) wrench onto the collar to secure this adjustment.