AMS & Color
Replacing an AMS PTFE tube
A loose tube causes feed failures that look like a broken unit. Reseating fixes most of them; replacing fixes the rest.
By Michael W. · Published October 5, 2026
Reseat first, replace second
Most PTFE tube problems are a seating problem, not a worn part. Push the tube fully into the connector until it stops, then tug gently — if it holds, you are done, and you have fixed it for free.
Replace the tube when: it will not stay seated, the end is deformed or flared, or the inside is scored along its length by abrasive filament. A scored tube adds friction that never goes away.
Replace the connector collet when: a known-good tube will not hold in it. The grip comes from small teeth inside the collet, and they wear.
How the connector actually works
These are push-fit collet connectors. Inside the opening is a ring with small teeth that grip the outside of the tube; pushing the tube in lets it pass, and pulling back makes the teeth bite. The release button or collar pushes that ring forward so the teeth let go.
Two consequences worth knowing. First, you must press the release before pulling, or you will damage the tube end by dragging it past the teeth — which is how a reseatable tube becomes a replaceable one. Second, a tube that was pulled out without the release now has a scored or flared end that may never grip properly again.
The procedure
- Unload the filament from the affected path. Working on a loaded path risks snapping filament inside it, which creates the problem you were trying to fix.
- Power down the printer and the unit.
- Press the release on the connector and hold it while you withdraw the tube. Never pull without releasing.
- Inspect the tube end. Flared, cracked or oval means replace. Clean and round means reseat.
- Cut a fresh end if replacing — square across, not at an angle, and deburr the inside. An angled cut will not seat evenly and a burr catches filament.
- Push fully home. Partially inserted is the original fault. Push until it stops, then tug gently to confirm the teeth have bitten.
- Reload and watch the first load all the way through before trusting it with a print.
Why this page does not recommend a specific part to buy
Deliberately. PTFE tube for these units is specified by outside diameter, inside diameter and length, and the correct part varies by printer and by which segment of the path you are replacing. Recommending a generic tube here would be more likely to send you the wrong internal diameter than to help, and an ID that is slightly too large lets filament wander and buckle — a worse fault than the one you started with.
What to do instead: identify the segment you need, get the dimensions from your printer's own documentation or the spare-parts listing for your exact model, and order against those. Generic PTFE tubing of the right specification works perfectly well; the specification is the part that matters.
More broadly on which spares are worth keeping before you need them: spare parts worth stocking.
When the tube was not the problem
If feed failures continue with a correctly seated, undamaged tube, go back through the feed diagnosis — a snapped filament end elsewhere in the path and a binding spool both survive a tube replacement untouched. And if filament is arriving at the hotend but not coming out, the problem is a clog, not a feed.
Questions people actually ask
How do I remove an AMS PTFE tube?
Press and hold the release button or collar on the connector, then withdraw the tube. Never pull without releasing - the collet teeth inside will score or flare the tube end, which turns a reseatable tube into one that needs replacing.
Does a loose PTFE tube cause feed failures?
Yes, and it is one of the most common causes. A tube that has worked slightly out of its connector leaves a gap, and filament arriving at that gap catches on the shoulder instead of continuing. Reseating it fixes the fault for free.
When should I replace a PTFE tube instead of reseating it?
When it will not stay seated, when the end is flared, cracked or oval, or when the inside is scored along its length by abrasive filament. Scored tubing adds permanent friction. If a known-good tube will not hold, the connector collet is worn instead.
Can I use generic PTFE tubing?
Yes, provided the specification matches - outside diameter, inside diameter and length. The specification is what matters, not the brand. An inside diameter even slightly too large lets filament wander and buckle, which is a worse fault than the one you are fixing, so get the dimensions from your printer's own documentation.
How do I cut PTFE tube properly?
Square across rather than at an angle, with a sharp blade or a proper tube cutter, then deburr the inside. An angled cut does not seat evenly in the collet and an internal burr catches filament as it passes.
Sources
Read this next
- AMS not loading filamentThe four real causes of an AMS feed failure in diagnostic order, three of which cost nothing and take minutes.
- Spare parts worth having before you need themWhich spares to stock before a failure and which to order after, judged by how long the machine sits idle waiting.
- Clearing a clogged nozzleThe procedure for clearing a clog, plus the four causes behind it - because clearing without diagnosing gets you a repeat.
- Maintenance that actually mattersThe five maintenance jobs that change print quality, in priority order, plus the consumables worth stocking before you need them.
- Running TPU through an AMSWhy TPU buckles in an AMS path, what genuinely helps, and why direct feeding is the answer most Bambu owners arrive at.