Filter started making weird noise

[Betta113]

I have the AQUARIUS AQ0080 Aquarium Mini Internal Filter that came with the Aquarius Aq15005 Aquarius 5 Rounded 5-Gallon Aquarium Kit. I have had it running for almost 2 months with no problems.The tank has a low bio load, only 1 betta. Only once did I have to reseat the filter motor when it began vibrating. Last night it occasionally started to make a weird sucking noise alternating with a large expulsion of bubbles. It stopped after a few minutes, but then started again this morning when I was leaving for work. Again intermittently. This evening it started again so I took it apart and cleaned everything. I put it together and plugged it in and it was running fine for bit but started the same noises again. I shut it off and poured tank water over the filter and it was fine again, but then began to make the same noise. I raised the filter cartridge up a little and the noise completely stopped. My new concern is that when I looked in the top of the filter the back of the cartridge is almost fully covered with water while the front is only covered 1/3 to 1/2 way. Is this OK or should I be concerned that the one side is not covered enough the the bb will be harmed? I don't remember how might the water level was on each side before this.

[madagascariensis]

Try finding the area where air is leaking into the filter system. It might be a loose or cracked tube or other component.. As for the water level discrepancy it sounds like your sponge is clogged. Try giving it a good rinse in dechlorinated water.