Hello, I can help you with this. This mold and soap scum combined and is common on front loaders. I can give you some tips on how to reduce the gunk and help prevent more build-up but there is no way to completely remove it.
You can run a few loads of vinger (1 cup per load) only, no clothes as well as purchase some long bristle brushed like pipe cleaners and scrub what you can reach. Depending on how soft you water is you should only use about 1tbs of detergent per load. Only increase if the clothes are not coming out clean.
In order to prevent more on new stuff when you get a new machine, you must leave the door open or ajar at all times when not in use. You must also wipe up the gasket after every load. Let me know if I can assist further. Thanks, Sam