I have been having problems with my tumble drier (Asko T794C) thermal protection going out frequently and decided to have a look.

The tumble dryer is a built-in so the air intake is on the front panel:

[![enter image description here](https://i.stack.imgur.com/1s8J7m.png)](https://i.stack.imgur.com/1s8J7.png)

Upon a closer look into the air intake I found what I thought was a really bad case of lint buildup.

The air duct is a plastic case which is really hard to open without disassembling the whole device, so I made a hook out of a knitting needle and started to pick the lint through the front grate.

Here's what I ended up with after an hour or so of work:

[![enter image description here](https://i.stack.imgur.com/pnX2em.jpg)](https://i.stack.imgur.com/pnX2e.jpg)

and from the looks of it there's more where it came from:

[![enter image description here](https://i.stack.imgur.com/AIiZVm.jpg)](https://i.stack.imgur.com/AIiZV.jpg)

At this moment I'm worried if it's really lint and not some kind of thermal insulation or something like this.

* It is much more dense than lint usually is. It's almost like felt.
* It looks like it has quite long fibers and sometimes whole pieces of fabric:
[![enter image description here](https://i.stack.imgur.com/RNTHim.jpg)](https://i.stack.imgur.com/RNTHi.jpg)
* It looks like it's built up in layers of uniform thickness (about 1 cm thick, you can see it on the grate photo).
* It does not seem to block the air stream. When I turn the machine on, I can feel the air coming in alright.

What is this stuff? Should I continue picking it out?

Update:

I found schematics for my machine:

[![enter image description here](https://i.stack.imgur.com/lrJKT.png)](https://i.stack.imgur.com/lrJKT.png)

and this stuff seems to be what's left of part 6260:

[![enter image description here](https://i.stack.imgur.com/9mfOK.png)](https://i.stack.imgur.com/9mfOK.png)

Any idea what could this be and what could it be used for?