Some exhausts do finish in middle as when moving air flow drags fumes out under body.
The pipe is standard nylon pipe, loads on eBay, you just need to measure outer diameter and inner diameter
As for releasing it, if you press the outer collet into the main body you can pull the pipe out. Might be stiff but it will pull out.
You can clean the inner holes then with silicone spray as there will normally be an o-ring in there that probably needs lubrication by now.
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