Fulltiming:
When I first took delivery of my 1999 Newell the water level in both toilets was too low. I called the service department and they explained how to adjust the water level. When I turned the adjustment knob, I must have turned it too far and the water ran continuously. I turned it back the other way (to close it) and the flow of water stopped and the toilet flushed properly.
I don't know if yours just got out of adjustment, but maybe you could try what I did. Newell Service department can describe what the adjustment knob looks like (it has been 6 months since I fooled with mine & I can't remember what I had for breakfast this morning).
So give them a call. Good Luck!
Tuga Gaidry