It kind of looks likes transmission oil stains Serious Repair.
Washing machine leaving grease stains on clothes. We do not use bleach or softeners in this machine. As the grease enters the tub it stains your clothes. Then let them dry outside and dont use the dryer.
Place an old towel or cardboard under the stain. Mildew has been a big problem and can cause a blackish greasy film. You dont tell me how your cleaning the washer but hot water and bleach is the way to attack this particular problem.
You can try using a wachine machine cleaner to see if you can remove the issue but if this is the case the inner tub will need to be remove and both of them cleaned. Certain chemicals minerals and impurities in the water can leave noticeable stains on garments. Then wash an old towel white is best to see if the oilgrease is on it with your regular detergent on warm or cold to test it out.
Rub a small amount into the stain with your fingers or a soft. Before you throw your clothes in the washing machine with some liquid laundry detergent and fabric softener the first thing to do to remove oil stains is to pull out the grease. When theyre dry check for oil stains.
Run the washing machine on a full cycle with hot water. A third possible reason why your washing machine is staining clothes is the presence of hard water. It is possible that during cycles without the bleach it is leaking back into the tub.
A more common problem is transmission seal failure. Wash the garment in warm water. Soak the garment in hot water.