I suspect electrical interference is disrupting the operation of the scanner motor or sensor. The problem you are experiencing may also be early signs that the scanner is failing.

If the problem is interference, you can attempt to identify the source. Remove potential sources, one by one, and take a test scan after each one. When you get a clean scan, reintroduce the potential sources, one at a time, again taking a test scan after each one. When the problem returns, you've found the most likely culprit.

Sources of interference include:

• Other nearby electrical devices, especially when too many are plugged into the same outlet.

• Problems common in older buildings, such as bad electrical wiring, improperly grounded outlets, or otherwise unstable electrical source.

• Nearby microwaves. They do not need to be in the same room.

• Anything that requires a large amount of electricity, such as air conditioners, laundry machines, refrigerators, and freezers.

• Failing power supplies or adapters. If your high-frequency hearing is good, you may be able to hear an abnormally loud hissing (often a bad capacitor).

• Improper grounding within your computer, especially if you are using a different one than before. If using a laptop, you can try using it on battery power.

• Nearby fan with a motor that's gone bad. If your computer has a fan, it also could have gone bad. Suspect if the fan is dusty and has trouble starting up. Vacuuming the dust away might help.

• Capacitor in computer or scanner that's gone bad. It should produce a hissing sound. In some cases, the specific capacitor can be located by its sound.

Other causes of lines in scans are unlikely in your case. They include:

• Newton Rings. Circular lines caused by contact between sensor and film. The rings farther from the center are closer together.
• Debris on the scanning plate. This is more common with document feeders.