Epson Perfection 4490. When scan head nears end of travel it begins to clack loudly, acts like it might be stuck, but then stops clacking and resumes return travel. When it occurs, scanned docs have dark vertical lines beyond the bottom of the scanned doc.
My TX100 has a similar fault, and I will try to get back to you as soon as I know, but as a technician,it looks as if there is an alignment or lubrication problem with the slide.
Mine has been getting worse from new, and after about 100 scans has gone in for a warranty repair.
It is clacking loudly and needs repair before it fails.
back in a week if i can... Peter
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix scanners.