My Vectra L1 started to get the bubbling on the motor side of the impeller housing as well, it still runs but I wanted to address the issue before an event occurs. I called ecotech and after putting a presentation and pictures together for them to review live on the phone with me, they said they will send me a new replacement pump which is the upgraded L2.
I love ecotech for standing by their product. I am sure if people make enough phone calls about their issues, the engineers will design and make the pump more safe, reliable and robust. Hands down, their customer service is the best which is why all my pumps are Ecotech. (4 x Mp40's and vectra soon to be L2).