Has anyone figured out what the sticky stuff that clogs up the sunroof drains consists of ?

I got the driver's side reassembled and working again but I might pull it apart and add a splice (3/8" copper toilet supply line - it is all low pressure plumbing, right ? ) to take the tension out of the line.

One of the initial problems looks like the tubing down from the sunroof drain shrinks lengthwise and pulls out of the rubber firewall fitting.

On the passenger side the rubber gizmo is plugged up with some sticky junk. I can't blow through it but about 40 psi will get through it. But it does not remove it. I'd go after it with a solvent if I knew it wouldn't kill the rubber piece. Currently I'm marinating it in dish soap.

Anyone had luck clearing these ?

Thanks

Greg