I have a 2 year old (but only really used properly for a year) HP ScanJet 7650N network scanner with auto document feeder on my desk which refuses to feed documents.

The rollers simply won't lower onto the paper in the tray.

Has anyone got any ideas as to why? I am not keen on spending 143 on a new ADF unit, and certainly don't want to buy a new scanner for 500+...