Battery operated flush urinal won't flush after installing new flush valve. Old flush valve had a small break in the bottom of the flush tube. After installing new flush valve it operated fine for 2 days. Then you could hear the flush motor run but no water would come through. Took apart, didn't see any problem, put back together and it worked fine for a day. The next day checked it in the morning it flushed as good as it did after reinstalling flush valve.but quit again hours later once again you could hear the motor running but no water. Replaced batteries thinking maybe they were weak still no water. Does any one have a suggestion?