More durable / wear-resistant orings for Quark?

Hope this is the right forum for this question...

My Quark Mini Titanium lights (I have a Cr123 model and a AA model) both have a slight problem.

Over time as I use them, the o-rings are wearing down, even though I try to keep them lubed with the included lubricant that came with the lights.

Black crud, which seems to be a combination of lube and oring material that has worn off, accumulates over time. Sometimes chunks come off too, little black chunks of the orings.

I'm not sure what kind of orings these are, but I'd like to replace them with a material that is more resistant to wear, so I don't get the black crud from oring wear.

Any ideas?

A thinner o-ring and/or change of lubricant may help... that is... if the problem is not with the machining of Mini's thread cutting into the o-ring. Most of my stiff o-ring problems are easily solved by using Krytox as the lubricant.