Try moving the steering wheel back and forth as if to clean away crap. Then try to reset it by disconnecting the battery for 30 minutes or more.
If it goes back on, then you can try replacing parts.
Also once you disassemble, you might just be able to directly clean the ring,brushes etc.

Do an archive search.
My w126 had intermittant srs light. Cleaning helped. no problem now.

BUT my C280 has it now. Goes off after 3 minutes.
Can't reset via battery trick.

__________________
1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD