Bailer tubes....
If your filling up rather than draining, I'd check two things. The position of your tubes. They are suppose to be routed in a specific way. Which is, in a loop. The loop generally keeps the upper part of the hose above the water line, so that you can't just bring in water.
Did you make any changes to this system as to the way it is suppose to be laid out? There should be 8mm tubing connected to and elbow then over to the bailer. There are two of them.
The other thing is, where the vacuum is created as it passes into the pump, look for restriction. If there is any restriction, a vacuum can't be created.
I have also heard from others with this problem. The disconnect them and put in an auto bilge pump. Good luck........let us know what you find out.