Before this engine hit 20 hours the tell tale would only work intermittently. I took it to an authorized Tohatsu mechanic who replaced the impeller (not a warranty item) and it seemed to do the trick. The impeller he removed looked new, however. I ran the boat another 10 hrs over a couple of months and flushed the motor after each use. After sitting for two weeks, I went out to run the motor and again no tell tale stream. The last time I ran the motor it was fine. I use a large water filled drum to run and flush the motor. I removed the lower unit and the water pump and found an impeller that looked partially melted, like it had been run for a while without water. I ordered new gaskets, impeller, upper housing and liner and reassembled the unit. Cranked up the motor and no tell tale. Removed the lower unit and applied hose to intake screen and water flows ok. Also ran water up through the intake pipe in the upper unit and water flows freely out the tell tale