Right Rear Water Drain Problems Into Trunk SLK230 2003

[DecoThom]

I could not get the drain hose to unclog from top or bottom. So, I pulled it out of the bottom harness area to let it drain into the cavity behind the rear wheel. (The inlet to this hose is the forward right corner of the trunk lid.) After a torrential rainfall, I found that the cavity did not drain properly. I found that I can push my finger up through the about inch wide rubber drain tube and press the bulb several times to get water to flow.

How do I remove the bottom harness to re-install the drain hose? The harness is behind the rear wheel, and hugs the bumper shell outer wall.

How do I get the cavity drain to work consistently? I think I can snake a shop vac hose in there with a reduced size hose, and vacuum out debris, flush, repeat, etc.

Do I need to silicon seal the upper part of the drain to prevent water travel down the PSE wires into the actual trunk area/not the farther right cavity.

Note: I already cleaned up the PSE, and need to solve the source of the water leak and resultant PSE failure.

Thanks in advance.
Thom