I am rebuilding a 1995 spx that had an overheating issue when ran hard. I bought it in pieces for cheep. The previous owner said it had a low water flow from the pump when they disconnected the lines from the motor, so they took it all apart and never put it back together. I have the pump off and tried to blow air through it backwards but it has a lot of restriction, is this normal or should air pass freely through it. Is there a way to make sure the main water passages in the pump are clear before I reassemble it.