Do you want to remove the arm rest plus the shaft or just the arm rest itself? If it the arm rest itself then you do not need to remove the seat cover.

IIRC - Pry out the circular rim of the big push button, remove the button. There is a big circlip holding the arm rest to the shaft. Remove it and the arm rest will slide out.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.