Front Load washers/Dryers Problem

[Disney Ontario]

Hi. we have a front load washer/dryer about a year old. DD16 has just started to see long lines on her light colored sweaters, she thinks it could be the dryer. Any ideas what is the cause?

 

[chager]

My first thought is it is something she is washing or drying with them. Maybe they are being seperated from dark clothes? I know I often will through my jeans or work pants in with whatever cause I have washed them so much already. If it isn't a coloring issue is there something with a zipper that could be catching on them? Or have you started using a new softner or detergent? That is all I can think of.