I noticed that the cost of a new replacement ABS pump for my 420SEL is $2100 from one supplier. Mucho deneiro. Ones listed on Ebay seem to be quite cheap considering how expensive the part is. What are the symptoms if it is going bad? Worth buying one to have around? Are used ones generally good?

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Der Panzermann und Fraulein Fahrvergnuegen

1991 420SEL 201K "The Big Blue One"
1985 300DT 205K chassis/285K engine nee California emissions "Goldbug"
1983 300TDT 255K "The Womble"
1983 300 DT 214K "Sea Sprite"-Rear-ended a truck
1983 300SD 285K "The Donor" Gave his life so that others can live
1980 500SL Euro 105K "Der Panzer"