@zachvat @ross I have a HL5240DN that I bought in the early 2000s. Still going strong.

A year back I could not find the correct cartridge, so I bought a different Brother cartridge, popped the top off each, then poured the toner into the old one and put the top back on. Another several thousand pages before I need to worry again.

It's easy as long as you are careful 😃

So even lack of correct cartridges can't kill them.