I salvaged a new unopened toner cartridge that I found in a dumpster
behind a rental place that has home furnishings, printers, etc.
It was still in the original plastic package.
Because of my experience with Brother laser cartridges, I was able
to remove the "plastic stopper."
I used a funnel into my empty Brother cartridge and poured the black toner
into it.
There was some cleanup of the spilled toner.
Here is a page I printer from the refilled cartridge.
What do you think ?
Looks perfectly.
Recycling toner from a discarded cartridge. 
I love it 
Very nice! 
Just curious, do laser toner cartridges have chips that tell them how much ink they have left? Would the empty cartridge need "resetting"?
I've only ever had Inkjet printers and hated how certain models would insist the ink was low despite printing perfectly well up until the chip said so.
That is why you should go to black and white laser printers.
They use way much lower toner that lame inkjet printers.
Proverbs 19:20 ESV
Listen to advice and accept instruction, that you may gain wisdom in the future.
Well done Andy!
FYI if the printer the toner is made for looks similar to yours chances are the toner is the same, even if the cartridge doesn't fit, maybe a printer 5 pages a minute faster will have a different cartridge but same toner.
You could take the chip from the new toner and put it on the existing one, that would fool the printer totally.
