I had to have my SOV replaced. I realized I had a problem after parking the vehicle and it sat overnight. I came out to my car in the morning and there was a large puddle of fuel on the driveway. Mechanic identified it was a leak with the SOV and repaired it. I can't remember if he just did a seal or replaced the whole thing.
I think you have the right train of thought to fix it. Start with the seal. If it persists, replace the whole thing.

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Ed
-1984 Mercedes 190D 2.2 5-speed gray market(bought@30,000 miles) (Sold back to original owner@170,000 miles)
-1999 Mercedes E300DT (245,000 miles)
-1999 Mercedes S500 Grand Edition (80,000 miles)