Trouble with a junior enlisted soldier. Any advice?

I was an NCO before cell phones and text messages. Battle buddy system.

That's an easy one...initial counseling. It will outline your standards, expectations and their duties as a member of your team/platoon/unit. This should also outline the possible consequences for failing to meet those standards and expectations.

Use the E-4 mafia! Find some high speed E-4's that have stripes on their mind to peer pressure the hell out of him. I am sure the 1SG and the CSM have grass that needs to be mowed, they always do. Take his free time, nothing like extra duty to get young troops attention.

get to know your guy...believe it or not you are his big brother, father, uncle etc. his leader and mentor. His welfare is in your hands and you are charged to take care of him. Find out what makes him work. I hope that no Soldier enlisted just to get a paycheck and that they joined because of their patriotism and urge to be the change our country needs. We all have 10% of soldiers that will engulf 90% of our time but I hope soon that little light goes off and he starts getting "it" good luck to you. Remember, talk to him and then counsel. It's a tricky balance at times brother.

The best thing to do is counsel him/her. Be sure to cover: What he/she has done wrong (include the AR section they're in violation of), what the consequences are, what your expectations are and the actions (training) to improve those areas. In these type situations I use a; check in time schedule (be creative, but remember; the training must fit the crime). Counsel him/her once a day for each failure(s) to comply with the expectation.
Keep your leadership up to date on each incident. If it goes on long enough, recommend him for chapter due to failure to adapt.
You are an NCO now. You're not going to have time for these childish activities. They need to know that. Reinforce their ego with things like, "you're a grown man/woman and I expect you to act as a responsible adult". Etc.

You are army, not a burger king manager, if doesn't go to his duty section that's "failure to repair " and disrespect to a nco, both no-no in the ucmj, stop the political correctness and lock his heels

I haven't read through all responses but most people have nailed it. Counseling all the way.

You need an initial counseling to let your Soldiers know what is expected of them. This needs needs to be followed up with counseling sessions every month to track their progress and realign them if necessary.

If the Soldier continues to not meet the standards of the unit, and more importantly the Army, you need to start hitting him (or her) with negative, event oriented counselings. This paperwork will be necessary for you and your command team to take appropriate action against the Soldier. Whether that be punitive actions or separation.

The Army deserves the best and relies on it's NCO Corps to provide it.

I've come across that situation more times that I can shake a stick at - ESPECIALLY in BCT-land, where Privates think they know what they're doing. I'd consider taking that PV2 aside (if female, remember she needs a Battle Buddy) - and let that Soldier know it's in his/her long term career interest to acknowledge having received an lawful order with a Yes Sir/SGT as a response. Since you can't read minds, that's the only way you'll know whether he/she heard and understood your directive.

A NCO will not have a problem with a Soldier but a Sergeant will. It takes a NCO to lead Soldiers and model the Army for them. SGTs, however, wears the rank of an NCO and must be groomed by the NCO support channels and at times the Chain of Command on how to exercise the duties of an NCO. Soldiers don't fail except when the leadership fails them. The source of support for a Soldier is their first line supervisor, section, team, and Squad Leader. Observe this Soldier and find out what motivates him/her, seek to understand his desires and find common ground to build trust. When you gain the TRUST, they will do anything for you. You will be a great NCO when you seek to take on the hard headed and turn them into great Soldiers. You got it. Do some gut check and the answers lies within.

I had a Soldier once who was chronically late to formation. My solution was additional training on formations; enter the Coin Platoon.

My problem Soldier was issued: 1x $1, 1 x .50, 4 x .25, 10 x .10, 26 x .01.
Coins denoted different positions within the platoon, heads up/down denoted different team leaders or weapons leaders.

Problem Soldier was to be at Company formation prior to scheduled formations with his coins in a standard formation; distances between coins were changed regularly to keep Soldier on his toes. Solider reported to 1SG his platoon's accountability status when required.

This was done for two weeks. Failure to participate or be late would escalate to Company Commander level.

This "remedial training" was annotated on the individuals counseling statement. Needless to say, my Problem Soldier got the point. Formations were no longer an issue.