I fix things for a living, from plumbing to a bike for a friend, but no living off fixing bike, other than a good time, a beer or two and some nonsense.
Problem with an O,ring under steady and repetive compression is it does take a set and will not continue to function. It is designed to be a seal and that is about it. Some will not withstand oil, or brake fluid, so you do have to pick those that will, others will not take the sunlight and quickly crack and deteriorate.
I have the perfect fix, a member on this site told me about using two little washers under and between the two halves of the anti dive gadget.
So I trotted off to Napa and got two small copper washers that will just fit between the two halves of the thing, naturally this leaves a gap so water and dirt can enter........so I placed an O ring around the top section, one that just fits, so now when the sections are bolted back together the o ring does compress enough to seal out the weather, but the washers do not allow it to compess too far, so now you have a good secure fix , with a weather seal.
This really does take most of the harshness out of the front end, not all of it, but a good majority of it. Makes a nice ride actually.
Does not totally disable it either, front will dive about 3/4 or an inch or so during an emergency stop and then the gadget works as it should.
This also takes the constant stress and tear off the left fork and the seals. And if you do choose to carefully use the front brake in a rough curve....not that you should, but sometimes it is cool......no more crowhopping around the corner.
Best .27 cent fix I have ever seen.
Oh the fellow who asked about what is the proper torque on the two allen head bolts.......well just secure, do not sweat the small stuff.....as a rule of thumb with any allen head bolt, small like that, I use a standard allen wrench.....no not a T handle that you can strip heads out with, just a regular allen, and when you see the shank of the allen just start to flex.....that is enough.