Samsung scx-4521f lines on feeder scan

Hi there,
Youll find that the most common problem with fax machines is that the scanner head that the paper passes over actually gets gritty and dirty. Remember it only takes a spek sitting in there.
Try a damp cloth (not to much Water) and wipe down the sensor reader, It will take a little bit of trial and error but mainly this is the common problem. also try wiping down all the wheels and rollers that the paper runs over as well. Otherwise it could be the recieval end that has a dirty paper feed wheel.
Sometimes it is also common that the internal scanner/sensor reader wears out and needs replacement.
IF this is the case its generally cheaper to buy another fax. Hopefully the above helps for you so you dont have to buy another one
Cheers
Steve

check the scanner glass it might have some dust on top of it clean it with a soft cloth properly. it should solve your problem