The OE rope didn't seal on the last overhaul. I've heard you can fish a new one on using a piece of wire, but since the last one didn't seal when installed on the bench, I'm a little skeptical. Any other options (aftermarket 2 piece) or suggestions?

 

While I have done as you say on an old Chevy members of another forum I hang out at have said there is some sort of Pin that stick into the Rope seal where you compress it into the Groove on Mercedes.
If this is true it prevents you from pulling out all of the old seal and even more so installing a new one.