When do you know its time to change the coupler?

One of the reason that you didn’t get your 3d printing as you expected is your coupler. Maybe this, will create under extrussion or block the nozzle.

After many hours of printing high temp filaments like abs your coupler will get burned on the edge and create drag.

What’s the coupler and why should I care?

Your coupler is one of the softest parts of your printer, and susceptible to a lot of wear and tear. The PTFE coupler (on the Ultimaker 2, 2Go, and 2 Extended) has a lifespan of about 500 print hours with PLA. It will last fewer hours with high temperature or with abrasive materials like CPE and ABS. The only way to check on the condition of the coupler is to take the printhead apart.

If you’re having extrusion problems, first check that your printer is clean, well lubricated, and that the Bowden tube is in good condition. If all is well in these areas, then the next thing to check is your PTFE coupler. You can check your number of print hours in the printer’s menu under Maintenance / Advanced / Runtime. The coupler on the Ultimaker 2+ and 2+ Extended machines are made of a tougher material (TFM) that should last longer than 500 hours, but it’s still worth checking print hours if you are experiencing poor print quality.

Over time, couplers can become widened out due to the heat from the nozzle, and the passing of filament through it. A ragged edge may develop, and the hole can become too wide. It may also be discolored. If the coupler widens out or develops a lip, then it should be replaced in order to ensure smooth filament flow.