You can screw off the white nut on the bottom of the bowl and remove the bushing on the inside and change the white gasket on your bowl. Sold in singles (not packages of 4 as per diagram below)
Bosch recommends to change the gaskets on your bowl at least once a year.
263847 Cover282724 Splash Ring (3 Tab) 049607 Drive Bushing Set020887 Bushing047972 Gasket for Bushing 020888 Nut153032 Gasket for Drive Pin 019608 Drive Pin