M28a printing blank sheets

[Elroch]

Printer: HP LaserJet Pro MFP M28a

Computer: Windows 10 64-bit PC

Printing just outputs perfectly blank pages

Software says cartridge is 50% full, 200 pages to go.

External test page print gives blank page like all other printing

Internal test page print via software does nothing

What is likely to cause these symptoms?

[Valsimot]

Copy of original document also blank page?

On the toner access door, there is a small plastic nib that is used to open the laser shutter if it gets broken laser is shut and the printer prints/copies blank pages.

Not your printer model but it should look like :

And here we have it broken:

[Elroch]

I can't identify the feature you mean for sure on the M28a. Here are a couple of photos.