Brother HL-2270DW Out of Toner - How to reset the Brother TN-420 tn-450 toner cartridges

I recently purchased a Brother HL-2270DW. It printed less than a ream (500 pages) with the cartridge the printer came with. It said it was out of toner - it was supposed to last 700 pages.

Apparently Brother installed a "flag gear" on their toner cartridges that slowly moves as you print and when it reaches a certain position and triggers a sensor the printer will refuse to print and says to replace the cartridge. This is caused by a developer rotation gear. Generally it will want to stop based on the dot count, and toner concentration to avoid running the toner cart empty resulting in poor print quality. By resetting the flag gear to "continue" it goes to the number of developer rotations before stopping which is typically the longer of the two. 

When a new toner is installed the developer rotation count and bias is reset by the new sensor flag. Also another thing to consider is that warm up, opening doors, one page print outs, and power off and on requires developer rotations lessening the life of the unit. So the more continuous printing you do the longer the life of the unit if you’re basing it off page counts.

All you do is unscrew this plastic cover on the gears and turn the developer gear and flag gear so they are set, 180 degrees. Then you rescrew the plastic cover back on. See this video for details

You can also manually refill it when it ACTUALLY runs out, but for now you should be fine.