Fuel Distributor Leaking

Hi,
I have fuel leaking into the airflow assembly and past the throttle plates into the lower part of the intake manifold when I press down on the airflow sensor plate. I believe my fuel distributor is defective on my 1986 190E 2.3-16V. I can hear fuel dripping when I press down on the airflow sensor with the engine off. I can also see some fuel on the lower intake manifold when I open the throttle plate. Is there a fix for this? Is it possible to just replace the fuel plunger o ring or do I need to buy the whole fuel distributor?
Thanks,
Steif