Can the Dryer drum seal if broken cause dark spots on clothes?
It appears on inspection that some of the seal inside back part of drum is bare.
Any ideas. And is there a video of repair for same?
Respectfully,
Dobbin
Montgomery County Texas
Here is a video of a Maytag dryer drum seal being replaced.
I don’t know if its anything like yours because you didn’t post your model number. I just guessed. More information = better answers. 
A bad seal could be causing marks on clothing. A bad seal allows the clothes to get between the drum and the walls. It also lowers your dryer’s efficiency and allows more lint to get into the dryer’s case.