my 2003 trx 350 fourtrax is not charging and when I remove one of the cables of the battery she dies! so I am guessing the inside charging coil is gone? Is it alot of work to change one and or could it be something else.I replaced the rectifier last yr with a new one if that has anything to do with it not charging.How can I test the coil?

my 2003 trx 350 fourtrax is not charging and when I remove one of the cables of the battery she dies! so I am guessing the inside charging coil is gone? Is it alot of work to change one and or could it be something else.I replaced the rectifier last yr with a new one if that has anything to do with it not charging.How can I test the coil?