I have this on my old Tumble Dryer, black sharp lines 2-5cm long, as if the clothes are caught or nipped between the drum and the outer case. usually the front felt seal is worn, leaving the smallest of gaps which catch the clothes. Generally easy to change the felt seal but it does mean taking the machine apart - some need the drum removing, usually from the rear, some can be changed with the drum in place by removing the front panel. Felt seal are between £8-15 online. Look up on the internet for your make and there is usually a site or video.
Nick, November 2016
