How often should the roller kit be replaced on the HP ScanJet Pro 2500 F1?

HP recommends replacing the pickup module and separation roller every 30,000 scans. Replacement is also recommended when the Maintenance Recommended dialog in the HP Scanner Tools Utility indicates they are due for maintenance, or if the scanner experiences repeated document jams. The roller replacement kit (part number L2748A#101) is a consumable and is not covered under warranty or standard service agreements. (Page 34)