HP PageWide Pro MFP 772/777 and HP PageWide Managed MFP P77740/P77750/P77760 - Removal and replacement: Document feeder reflector (MFP models only)removing and replacingdocument feeder reflector (MFP models only) | HP® Customer Support
HP PageWide Managed P77740z Multifunction Printer Software and Driver Downloads | HP® Support