I test mine many times a season. They do get gunked up with crud. You need to remove them from the housing and clean every little scrap of debris in the bilge and the pumps, then degrease the bilge and leave nothing but clear fresh water behind every time. when you flush your through hulls, flush the bilge again with clear water.OK, update on my old bilge pump issue. I cleaned the bilge this weekend and turned on the low water bilge pump from the helm and it just ran as before but would not pump (same issue as last fall that was supposedly fixed by my dealer). I tried to prime with hose but no go. Then I decided to test the high water pump by raising the float switch. This pump pumped but when I turned it off all the water came back in. My guess it was all in the discharge hose and never left the boat. How many of you have tested your pumps recently? Did both work as designed? I want to tear these apart but I'm still trying to figure out how to reach the rear low water bilge pump.