Riser visor slows brushes in standard position

Love this vacuum, but noticed the brush making a click when first starting. I cleaned the brushes and in the process of doing so, noticed that the brushes run full speed when I have the riser visor in the upright position (as if you were cleaning the sides of stairs), but slows or stops when I move it back to the floor cleaning position.

I removed the visor and checked that the spacer was seated correctly. Everything is fine there.

Any suggestions?