Dreamstation (DS1) observations

Any experienced cpap technicians here?

I recently attempted to change the air chamber in my 3 year old DS1 for the new one available without any foam. In the disassembly process I noticed an accumulation of a dark residue inside the case, which didn't alarm me because I knew the air path was segregated.

Replacing the chamber is straightforward and the new one is an exact replica minus any foam. While I was in there I decided to have a look inside the pump just because. This is where I noticed something that made me go "hmmmm...".

Using alcohol prep pads I swiped the inside of the pump circulation chamber and noticed the same black residue was in there. Hmmm... I thought that is supposed to be clean. I am anal about changing the filters (regular and xfine) and keeping the machine clean. There is no sign of this residue anywhere on the intake side.

Closer examination reveals the residue is on the impeller and both sides of the pump chamber. I have never noticed any residue inside the water tank or humidifier, but I empty and wipe those daily. I have never found any residue in the hose or mask. Whatever is in the pump is a 3 year accumulation.

Is this something normal that happens inside these machines as they age or is this the breakdown of the foam?

In the course of my pap therapy I have experienced worsening respiratory symptoms that I have consulted a few doctors for and have been treated with no appreciable improvement. I now wonder if this is the underlying cause.

I also disassembled the blower to inspect its cleanliness while replacing the air chamber. My Dreamstation 1 fan blades and shroud were clean. I was surprised to note that without the foam the machine is still very quiet.