There is a pawl up under there. It is held in by a cap that looks like it has a slot in it for a screwdriver. Take off that cap and look at the little pawl inside. It is made to follow the slot on the shaft as you turn the reel handle. If one side of the pawl is worn, it will pile up the line on one side like you say. You can usually pick up those small parts at Academy, Marks, or The Bait Shop in Bessemer.

since the ambassaduers have snyced line guides that typical do not, and should not, get lubed to hard, the line guide pawls are notorious for going bad. it is an easy fix however, just remove the pawl cap to check the condition of the pawl. and, you will want to take out the wormshaft to check for any damage to it.