When you turn the solvent manager pump to drain or fill, the the reagent move any amount in the tubing? If yes, even moving a few centermeters, then the pump is working and there is an air leak somewhere. The solvent manager pump is a very low pressure volume pump. The littlest of fitting air leak will not allow the reagent to drain or fill. Also, do you feel and vacuum at the small port on the top of the solvent manager pump when draining? Or can you feel any air flow from the bottom port on the solvent pump during a fill operation? If there is no movement of the reagent in the drain or fill lines, then the solvent manager pump will need to be replaced.