So today my 2004 SL55 decided that the steering wheel would not go up and down. Only in and out. I can hear like some kind of gear has broken and is clicking. Anyone ever taken the mechanism that controls the steering wheel apart before?

There is a coupler from the motor to the gearset that is usually the problem. Order one and replace it even if you have another problem. The job is not real fun because you have to contort yourself into position to work on it. Not difficult though.

I'm guessing this? https://www.ebay.com/itm/176339831727

203-462-06-78

Yep. After watching a few videos I see what was meant by coupler.

I'm still trying to figure out how to use WIS so I'm guessing I just need to remove that metal plate at the bottom of the steering column and I should be able to see the broken coupler at that point?

There is a pivot bolt with a clamp nut that attaches the column to the tilt gearbox. Remove it so that you can drop the column then take out the four bolts that attach the gearbox. That allows you to remove the gearbox, replace the coupler, and put everything back together.

Reading this, I do hope mine won't give up, ever. The piece looks sturdy enough.

It is typical Mercedes. The gearbox mechanism is machine tool quality, way overengineered. Then they put in a 10 cent plastic coupler for a failure point.