I think your over tightening them. I see nuts on the broken side, not wing nuts. Easy to overtighten when you have to use tools. :bigeyes:

Check the rings
 

It also looks like maybe one of the rings is upside down. If you look at the one shown on the left you can see a notch in it at the top. You don't see a notch on the other one. Now I haven't seen one of these particular tractors in person, I would venture to say that the notch should be on a "key" tab, on the back of the lamp.

After going back and looking at the photos, you definitely have one of the rings on upside down. the ring on the left shows the notch at the top the one on the right shows it at the bottom.
As I said there should be a "key" boss on the rear of the lamp, this is to keep it from spinning in the mount. If that Key is not lined up in the notch, it loads all the pressure into that point rather than around the whole diameter.

I believe if you put a new lamp in it and make sure hte rings are located correctly you won't have any more issues.

Switch to wing nuts, check for any high spots on the rings causing a pressure point, and as an added precaution, a bead of clear silicone around the rim of the bulb where it meets the ring will stop any rattling or wiggling that might be going on. Mine are going on 6 years without issue.

I did some more looking at my lights. One was cracked all the way across, but the other was just burnt out. I swiped some thumb screws from a 149, locked them in with blue Locktight, put a bead of silicon around the front of the lights and metal ring, and installed a set of vstar lights. Here is to hoping this set lasts. Thanks everyone for your input. I'll keep you posted if anything doesn't last.

https://c5.staticflickr.com/9/8268/3...dc226952_c.jpg

https://c1.staticflickr.com/9/8416/3...fd1d7ecb_c.jpg

https://c1.staticflickr.com/6/5642/3...834bd910_c.jpg

If you look at the elevation rectangle on the headlight.....about where your left wrist is and match that up with the depressions in the headlight ring (where you did not use sillycone :biggrin2: caulk), along with wing nuts, then you should no longer have any problems with your headlights.

Cub Cadet 123

I've had the notch matched up every time and I'm still not sure why they cracked so many lights.