Don't use WD40 in automotive business.
Take it to chicken barn and never remove it from there.
WD40 is wet lubricant, that attracts dirt.
For cables you can use silicone lubricant, or go to watercraft store and get special cable lubricant with connector, that will allow injection inside the cable.
Cheap plastics and MB just don't go well together.
I is sorta like the one you pictured just broken in different places but the same screw area problem. What is the color code of the one you show pictured, have found one online but show as Orion Gray part number A 163 919 39 20, took mine off but could not a stamped part number on the backside. Any thing you did to solve your problem would be helpful. Thanks Joe
Like edcarls mentioned, it is more of a shape/material/design problem. This has happened to both of my ML's. My ML 500's plastic cover just broke like a month ago after I sat down hard on my seat.
When you seat on the outside edge, the seat cushion will depress all the way down and will apply pressure to the cheap plastic cover edge, which will eventually break.
I am going to buy a new plastic cover and reinforce it with a thin metal washer and glue to help it from breaking.
AC
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2005 ML 500
Black, 18" AMG Wheels, 285/60R18 Falken Ziex ST/Z + Bi-Xenons(+ Drew's e-code mod), Yakima roof bars. Former vehicle 2001 ML 320 with 108K miles, when traded, and a large repair/defect history.
It's around $50 at the dealer, I'm talking about the mask on the side of the driver/passanger seat. Easy to fix. Just be careful with the wires going to the seat control switch unit attached to the backside when removing and re-installing and don't tighten the screws very hard when installing, or the new cover will crack also. The new cover is a perfect fit and you have to make sure that it lines up perfectly at the seam where it meets the mask in the front part of the seat. In the picture there's also a circular plastic plug. The old one from my original cover did not fit with the new cover and the plug is not included with the new cover package. I had to buy the plug separatelly, cost about $12. The screws are sheet metal screws black colored. Also, do not come with the cover and dealer could not provide them. I bought similar looking ones from Home Depot, I think they were #8 or #10 and fit well with the original hole except they are not black. Since the hole is recessed about 1 inch deep they won't show anyway. I still have the box and could post pictures, I also have the invoice somewhere @ home with the MB part number, if anyone interested of course. I'm not an adept of using plastic glues as they don't seem to hold very well on thin sections.