My condensate pump was running continuously. Had to be either a bad check valve, or a clogged drain line. Put some die in.
Pump comes on, die goes up the line. Pump turns off, die comes back down the line.
Sure enough it was the check valve. How to fix this? $120 for a new condensate pump, or $250 to have someone come and install one. :-(
it's the little pink thing in the picture. Costs about 0.005 cents to manufacture. Designed for easy replacement.
Best price I could find was at plumbersstock.com. $6.29 + shipping + low price order surcharge.
Hopefully I can remember to empty out the pan that's collecting the condensate regularly.
In case this helps someone else.