I've had cartridges fail or seen them fail many times, as I put myself through college by servicing consumer electronics.
My Transfiguration Orpheus lost one channel for no reason- they replaced at no charge, a Grado lost a channel, again replaced at no charge, a Shure suddenly lost output in both channels because apparently the magnet shifted. That one was old and we just replaced it.
My Transfiguration Orpheus lost one channel for no reason- they replaced at no charge, a Grado lost a channel, again replaced at no charge, a Shure suddenly lost output in both channels because apparently the magnet shifted. That one was old and we just replaced it.