In the early 1990s John became afflicted with Meniere's Disease, a disorder of the inner ear that usually affects both hearing and balance. It is characterized by episodes of vertigo, random and extreme fluctuation of sound volume, and by fluctuating or permanent tinnitus and hearing loss, which presented unique challenges to performances and recording, the resolution of these allowed an expansion of thought as to how sound production was perceived in terms of amplification and microphone placement, as well as refinement in left hand fingering and right hand fingering, percussive techniques, strum and 'string feathering'. In 2010 his right hand was severely mangled by a dog bite, again presenting unique challenges for John since his playing style incorporates use of fingers, pick, and various other sections of the right hand in bringing forth the tones he prefers.