I can't get good control over my ring finger of my fretting hand. The distal joint of that finger (D. I. P.) wo t bend much even using my other hand to bend it. Also when moving the ring finger from the Cchord to the A minor chord the ring finger catches for a second and then seems to pop into place. What's going on? Anybody know how to solve this? I'm a relative beginner. Just getting into the power chord section of Lisa's lessons. BTW, I'm 72 yr old.