Reposting after several months since I didnt get any answers the last time I asked.
I'll try to answer this.
Basically, Jimi Hendrix was in trouble with the law concerning car theft. The judge gave him a choice, jail or the Army. He chose the latter and enlisted on May 31st, 1961, at the age of 19. He did his eight weeks of Basic Combat Training at Fort Ord, California. He was not considered to be a good soldier in Basic training as he was declared unqualified on the shooting range.
Somehow, he passes (barely), and he gets sent to HQ & Company A of the 801st Maintenance Battalion of the 101st Airborne Division, stationed at Fort Campbell, Kentucky. His job was as a supply clerk with the Repair Parts section of the battalion. He is not interested in soldiery and requests his family to send down his guitar, which they do. He proceeds to basically neglect his duties while improving his guitar skills. He failed bed inspection three times, was caught sleeping on post and (according to the discharge paperwork,) "apprehended masturbating in platoon area while supposed to be on detail." He was deemed to have, "No known good characteristics." Was also labelled as an "extreme introvert." This is backed up by his First Sergeant (E-8), his Staff Sergeant (E-6), his Sergeant (E-5), a Specialist 5 (E-5), a Specialist 4 (E-4), and a Private (E-2). The last two were the ones that caught Hendrix masturbating in the barracks bathroom. He was given a discharge of "unsuitability — under honorable conditions" on July 2nd, 1962. His rank was a Private (E-2). Supposedly, Hendrix says that it was due to an ankle injury on his 26th Airborne Jump but that is unconfirmed. It is also suspected that he was discharged of "homosexual tendencies", but this is also unconfirmed as well.
In short, his stint in the Army, which lasted over a year, was unproductive for the Armed Forces but productive for his guitar skills.
Sources:
Military Records of Jimi Hendrix. (This includes enlistment papers, his performance at BCT and at Ft. Campbell and his dental records.)
https://www.warhistoryonline.com/instant-articles/jimi-hendrix-us-army-discharge.html?edg-c=1
https://www.wearethemighty.com/popular/jimi-hendrix-kicked-out-of-army/