[Bob Meadows]

The air dam on certain 240 models seems to be a recognised failing point at the screwed brackets either side of the front bumpers:~

One way to fix this is as follows: the screws go through the bumper sections into a small plastic vertical spigot that is part of the air dam- the failure point can be a split locating hole for the self tapping screws.

Obtain two plastic tyre valve covers and roughen the inner bore as well as the spigot.
Press the covers into an oval shape making sure that they can pass through the locating hole on the underside of the bumper, remove for the next stage.

Fill the covers with J.B.Weld with a thin layer also applied to the spigot (the adhesive doesn't like smooth surfaces- hence the keying)
Push the filled covers onto the spigot & run a little tape around the section as the weld can slump whilst drying- note the angle of the fitting and adjust to suit.

Allow the weld to dry overnight, once fully set push the air dam into place and with a scribe/pen mark the through hole point onto the tape for drilling a small pilot hole.
Carefully drill the pilot hole: you can now secure both sections with a stainless screw (flange head will give a wider O.D.) do not overtighten

You may find it easier to loosen the bumper side blades from the body- 10mm bolt from the bottom of the inner wing.
Another option is to use a "U" shape copper piece over the spigots and again fastened with the weld paste- valve covers work fine though.

I believe others have used cable ties for the above but for me the angles to pull the two parts together didn't look correct.
Trust it give you some ideas for the repair.
Bob.