I am testing a theory here ....
I rang the gong 4 times .... almost stopped at three because the third time it took health, and a pea-green fog made some of my nearby villagers sick. I ALWAYS train EVERYONE at least to trainee healer status by walking the newbies through the "strange plants" routine, so when that happened, I had healers running all over to heal those who were affected.
The first time, I had a EE ring it, and all of my tribe was pretty full on their health meters, so when I rang it, rainbows came out and the gong granted health.
The second time, I had a Master Scientist ring it and the gong granted wisdom.
The FOURTH time, I had a master healer ring it, and it granted health again.
What to note is .... THE LENGTH OF TIME BETWEEN RINGINGS ... I haven't rung it enough times, but I am thinking that if you let it fully charge and only ring it once in a while, not every night, you might get more positive results. Just a theory, but I rang it the very next night the third time .... and a week after for the fourth ... hmmmmm veerrrry interesting!!!