Looks like you have very little threads for a nut with a nylon insert. That type of thing is not especially prone to vibrating loose, but a drop of blue loctite is not a bad idea. The adjustment for the clutch is not something done very often. Most wet clutches wear pretty minimally dimensionally, the adjustment is mostly for variances in the case assembly. The idea is to have an adjustment for the throw-out mechanism to match it to the case and stacked dimension of all the parts. Once done it usually does not change too much unless you change something in the stack. Once you put it all together, adjust it once with just a bit of free play - that is there has to be an actual small amount of space in the adjustment so the clutch is completely engaged. If there is no free play, the tiny preload pressure might eventually allow the clutch to slip and burn. Once set, you only usually have to adjust the cable as it stretches. You can see how you always also need a little slack in the cable adjustment too, because if you take all the slack out, you could partially activate the throw out mechanism, preloading the clutch and again potentially allowing it to slip.
Make sure that you have the cable completely loose FIRST. Then you can adjust the throw out mechanism. Once adjusted, go back and adjust the cable.
