A plumber installed a new 19" round bathroom sink in the vanity. Same size as the old sink. We kept the same faucet and drain. The stopper is the lift rod to close drain, push rod down to open drain. The plunger won't hold the water in the basin. Called Moen, they sent a new plunger, and it won't hold the water either. The plumber doesn't know why. Has anyone got a remedy for this, a new sink that won't hold water is useless. Do they still make those old push in rubber stoppers?