The UPK-M Series knifes were designed to accommodate EDC use and handling minor debris and buildup was heavily considered with the implementation of internal gaps, pockets, and self clearing mated parts. That being said, you still need to maintain your knife, treat it like a firearm, you wouldn't expect reliable operation if you never took a moment to clean out the action once in a while. The All Stainless design was intended to be easy to use and maintain, it needs little more then a q-tip to clear out the internal pockets should some grit/sand or other hard particles start to foul up the action.
Cleaning & Maintenance
Bolt-lever is not engaging in one of the deployed positions (an open position)
Solution: It is likely debris buildup that is hard enough to block the rotating bolt-lever lobe from entering the pocket fully. Clear the slot and pockets with a fine tip tool, a common Q-Tip cut in half at an angle, this provides two stiff narrow tips to clear out tough grit, then turn it around a use the cotton swab side to catch and remove any of the loosened debris.
I did something filthy with my knife and need to clean it!!
Loctite 1167237 White LB 8014 Food Grade Anti-Seize Lubricant, with added optical grade cerium powder (my own concoction)
The Optical grade cerium was added to aid as a mating lapping compound to further improve the action as you cycle and use the knife, think of breaking in a semi-automatic handgun, I wanted the user to experience an improved action as they knife was cycled with regular use. You don't need to replace this, let it last as long as it does and use whatever lube you are comfortable with or just have around, some CLP will do just fine. My suggestion if you are using the knife on food, is to stick with lubes that are food grade, silicone based or look up the stuff I listed above. The knife will cycle without lube, but lube just makes things slide smoother, less friction makes for faster retraction and smoother deployment. And remember! a little lube goes a long way, too much lube and you'll quickly gather up your own special muck mix and end up cleaning it sooner then later.