I had one go on the 500 and trust me you do not want it to happen. It takes about eight attempts to do a U turn on a 2 lane road. Cost right aroun 400 if I recall right with labor. Well worth it unless you want a arm work out at the risk of saftey while driving your 126 ;)
Good luck

Benzman500, thank you. How many hours of labor did it take?

I'm working hard to make sure it's fixed by the end of next week.

Resealing a power gearbox is less than $30 in parts. I have done a few of them and yes it was scary at first but I managed well.

Any Mercedes shop worth their salt should have no problem at all resealing your old box. There is a reputable shop here locally that does them all the time, they bill it out for 9 hours but I have done them in about half that.

I dont recall for sure how many hours it was but for some reason 4 sticks out in my mind. But then again I did not pay the normal rate :)

thanks, four hours is what i was told it would take.

My 90 560sel was leaking steering fluid too,found the leak to be coming from a 19mm nut at the top of the steering box. Tightened that not ,and it has not leaked since. I don't know why that nut came loose,so before spending big bucks,try to find exactly where the leak is coming from. Clean the entire area,then start the car,you will be able to see where the leak is coming from.