Suppose, you are printing some urgent documents in your printer. And then, suddenly, there’s no ink on your printed papers. This type of situation happens to the best of us every once in a while. After all, we lead such busy lives that we forget trivial things like when to refill the printer toner cartridge. And then, regret our forgetfulness when we run out of ink. But we can avoid this from happening if we observe a few things. You don’t need to be an expert to know when to replace your cartridges. Just follow through with these clues below and you will be able to understand when to buy new toner cartridges.