If the black marks are from mould on the door seal, either clean with bleach solution or replace seal.
I suspect the this is oil which is contained in your drum bearing and leaks now that the bearing is worn/wearing. Try wobbling the drum up & down. If it has a lot of 'play', the bearing needs replacing.
It may still be chewing-gum residue on the outside of the drum. Do a 'service wash' to clean it. IE select the hottest wash possible (usually 90 degrees) and leave the drum and soap-tray empty.
Alan
September 2005