Tiny I think over the miles the cable wears a trough in the housing that can get dry and chattery. If you recall there used to be an old guy at the swap-meets that had a display of a smoot running speedometer,he sold a special lube for them . Mine runs OK but the hand rubs on the glass,at about 50 it's pretty smooth for 71 yrs. Also the 2-speed switch-over is fine.
