Dremel cutter or whatever you can, just get the headlight+bracket unit out of the car.

Next you need to separate the headlight bucket from the bracket. This is an operation fraught with danger, do it with care.

Look carefully at the three attachment points. The adjusting screw has a ball on its end, held into the mounting boss with a clip that looks like a safety pin. The danger is that a strong pull to get the ball put past the clip will often just break the boss at the point where a groove is cut in it for the clip. That renders the headight virtually useless.

Use a pair of pliers, maybe two, to remove the clip. When the clips are out, the bucket will fall off the bracket. Then put the clips back on. Watch out when the clips are removed, there is a spring in there that flies into the great never-find and you will need it later. It is made of unobtainium.

Remove remains of the offending bolts and install new ones, half an inch longer than the originals. The bolt head needs to stick out past the bracket so you can get a wrench on it, I put a half-inch length of thick-wall rubber tubing on the bolt, anything like that will serve as a spacer.

There may be another way at this point. Use a new bolt same length as the old. Make the rounded out hole in the plastic to have a non-round shape. Square, slots on two sides, something. Then put in the bolt and get it tight using a stack of washers on the other side. Fill the now non-round hole with some sort of hardening plastic stuff. I would use a 2-solution epoxy plastic cement, got some at ACE Hardware.

Or - you could get an "new" bracket on eBay.

Now you can install the "repaired" bracket. 10mm on the bolt and the nut. Put some anti-sieze on the bolt where the nut goes on. The headlight can be installed into the attachment bosses will a sharp push on the lens corner near the adjuster screw. Grease the ball on the screw first, it will pop right in. Note that removing the headlight in the future will be difficult, so be sure the headlight you install is the best you can get.

Long post, sorry. Maybe another guy will have a better way. This is the way I did it on my 1986 244.

Good Luck,

Bob

:>)