It could be a worn stud or worn nut. If it's really bad, you may need to install a new stud. If a new nut doesn't fit tight, you could try putting a jam nut on top of the rocker nut.
cotter pins?
Gotta have the correct torque specifications and tighten those nuts on the spring assemblies. Too tight,and they don't flutter right. Too loose,and they allow the rocker arms to wiggle out of whack. My apologies for not being more specific,I'm just a 'driveway mechanic'. You need to replace the locknuts for the rockers. I'm not sure if they are positive stop or not.
Your cylinder heads are most likely loose. Remove your rocker arms and torque the four head bolt nuts (four on each side) to 23 ft lbs. Then do a compression test.
Because the bolt stop is broken..they have a plastic bolt stop.
Hydraulic lifters are nonadjustable. Chances are the noise is coming from play in rocker arm, or ignition out of time. If you are sure it is the lifter, then it must be replaced.
green banana helps to stop the severe loose motions..
I'm not sure exactly what your working on but it sounds like a "heli-coil" would do the trick. Stop in your local auto parts store and ask them for a "heli-coil" kit to repair the size bolt you have. The kit will supply what is necessary to repair the threaded hole back to original.
I've had a pin fall off while driving, you're braking becomes erratic, car may stop suddenly when you are lightly hitting the brakes, You may also notice less brake power or hear a noise coming from the wheel
Pop out the light with a screw driver and check if the aerial is loose and letting water in.
Replace the gas cap with a new one and tighten it 3 clicks.
You must have a modified camshaft. The lift on the cam is to high of a lift and the rocker arms are binding on the studs. You need to use a long slot rocker arms to stop that. You also need to check the rocker are studs and make sure they are not cut in half.
unload the gun first. remove mag nut and barrel. Now the O ring and rings. Make sure to remember location and placement. Pull the bolt handle out, it comes straight out with a hand pull. In the loading port you will see the mag stop on the side. This stop keeps the bolt from coming out. When you push this stop to the side you will notice the bolt and carrier comes out the front of the action. Now take the bolt in hand. You can see the firing pin and what is needed to replace it. Make sure to clean everything while it is down. Replace in reverse. Best of luck.