My Sharp AL-1641cs won't print. Just keeps flashing red drum.

Reset the drum count by pressing "Clear" then "Exposure Mode" then "Clear" then "Exposure Mode"
Exposure mode is far left key on panel. You need to do this fairly quickly so that the display goes blank.
Once display goes blank then key in 24 then press print, then key in 7 then press print. You should now be getting flashing 000
Turn machine off then on and light should be gone.
Short version: C,far left,C,far left,24,print,7,print

SERVICE MANUAL AL-1631 AL-1641CS

you setting grayscale all text black thanks

Which reset are you trying to preform
the counter for the drum unit ?

If you saved the instruction when replacing the drum, did it give you a procedure to reset the drum count?

It could possibly be your drum or PCU assembly needs replaced. If you have your owners/users manual, it should give a definition as to what the symbol is.

http://www.retrevo.com/s/Sharp+AL-1641CS?rt=pd

Here is the location for your copier manual. You'll be able to view & download. Good Luck :0)