<https://community.ultimaker.com/topic/19249-how-to-tell-when-the-ptfe-coupler-is-bad/>
<http://schema.org/text>
"So I've had my UMO for a few years now, and it's been having an increasingly difficult time pushing material. Last time I tried to print something, I couldn't really push any material through and have spent the last week trying to clean the nozzle and figure out what the problem is. I have never replaced the PTFE coupler, and I'm wondering if that is the problem, causing restrictions and also contributing to the under extrusion I was experiencing when I could still move material. "
<https://community.ultimaker.com/topic/19249-how-to-tell-when-the-ptfe-coupler-is-bad/>