I work for a company the services coin washers and dryers at universities and apartments. I have been doing this for almost 27 years. I worked for Sears before that.
The washer has probably retained some soap film on the inside of the tub. Not the clothes basket, but the tub.
If the washer does not have a clean cycle, just run a hot wash cycle with no clothes in it. You can use the Alfresh tablets from the stores or something similar. Or vinegar. Put in a half gallon of cheep vinegar after the washer has filled up all the way (as far as it normally does) and an additional gallon of more hot water. You could put in the other half gallon and more water in the rinse cycle also if needed. The extra water is the secret to cleaning the whole inside of the tub.
The front door seal also needs to be cleaned with a soapy bleach mix. Using a toilet bowel brush or something like that will do the job. Do the door seal before the tub cleaning.
Backpacker and tent camper all my life. Motorcycle trips with a tent too 1978 to Present. 2016 Grand Design 380TH as of 10-29-2015. Now a New 2018 374TH-R Solitude as of 3-16-19. 10-19-18-traded truck for a 2016 Ram 3500 DRW Laramie Crew Cab 4x4 Long Box.