HP Laser is printing blank pages

[TNF]

Hi, I have a HP MFP M177 FW color laser printer and it's been working fine for about 5 years. Suddenly one day it printed one sheet that was only yellow. Then every sheet since then has been blank.

Info to rule things out:

• Unit never gets moved.
• No power outages, etc.
• No errors on the unit
• I replaced the black toner
• Drivers up to date
• No changes were made, etc, etc, etc.
• The unit works fine otherwise. I can scan to PDF, but I cannot run copies or print. Everything runs like normal when I try, it's just that the [ages are blank.
• I tried running tests from the PC, and tried running reports directly from the printer.
• I have never replaced the drum, because I never had reason to (maybe this is it?).

I was told by someone at a store that it could be "the drum". He seemed convinced. I asked if there were other internal parts like something that "charges" the toner (I don't know what I'm even asking), etc. he said no. But when I look online I do see mention of a "fuser".

Anyway, before I take this heavy thing in for repair are there any suggestions on what I might try first?
The connection is fine, the printer will act like it's printing but the pages are completely blank.
Should I buy a drum and see if that's the problem?

Any advice is appreciated, thank you.

 

[PeterBJ]

I'm no laser printer expert, but I think a drum doesn't fail abruptly, instead print quality degrades gradually. So I think the fault is electronic. Maybe a repair manual and a troubleshooting manual will be helpful?

Beware of high voltages inside the printer if you decide to troubleshoot it yourself.

Edit: see page 88 in the troubleshooting manual:

 

[TNF]

I'm no laser printer expert, but I think a drum doesn't fail abruptly, instead print quality degrades gradually. So I think the fault is electronic. Maybe a repair manual and a troubleshooting manual will be helpful?

Beware of high voltages inside the printer if you decide to troubleshoot it yourself.

Edit: see page 88 in the troubleshooting manual:

View attachment 14115

Well thank you very much for that. I did not even see that in there.