W210 sidemirror got hit & very loose. repair possible?
 

someone hit my side mirror housing on 97 E420. the mirror is still attached strongly to the car but it flaps around both ways quite easily. upon observation i noticed that there is a spring in the middle, it's still hooked to the car but it doesn't grab until i pull the mirror away. this is probably why it's so loose.

is there a way to fix this diy?

you more than likely need a mirror frame. the other end the spring attaches to breaks off when this happens. maybe its fixable, I've never tried as I don't own one.

If you search for W210 mirror, you will find a DIY fix to this issue. I had the same situation on my E300D-T, but the dealer tried to fix it at a cost of $100. The assembly loosened again, and I had to pay $450 for a complete new mirror.

This can be very irritating. When mine broke, I thought I was going to have an epileptic seizure when driving... the shaking at night with car headlights in the mirror was like a strobe.

I fixed mine ('98 E320) with 2-part epoxy, because I'm cheap. But you have to realize that the epoxy has a different thermal coefficient of expansion than the plastic, so it won't last forever. It will last much longer if you live in a location where the difference between winter and summer temperature is only 30 degrees or so, like south Florida, but if you live up north, expect to repair it every 12-18 months.