Had same problem with 420SEL at 220K miles. Started to buy a new seat frame and cushion, but before I did, I checked with my local MB mechanic for installation advice. He recommended an auto upholstry shop that does all their upholstry work. Good advice. A few hours and $100 later, the shop replaced the broken spring (singular) and re-padded the seat - feels like new. Saved a few bucks and learned a few things. The shop owner said he has fixed many MB front driver's seats with exactly the same problem. Maybe you have someone in your area who can do the same.