So both my 1800-1800ti don't seem to have the one way valve on the booster. At least not like the one seen on the 02s. Am I missing something or that's how they came from factory? The usual websites seem to show a valve like the one below, item #10
http://bmwfans.info/parts-catalog/NK-Sedan/Europe/1800ti-4-Zyl/jan1965/browse/brakes/brake_servo_unit/