I had one of these running for nearly a year until a week or so ago. I found the same water 'leak' issue with the power lead - but it would always cease after a certain amount had come out. I guessed there was a void in the lid that accumulated water and it just needed to drain. Sometimes that water would flow around the outside seal a little, but it would always be only a few mL and a couple of times drying with a towel and it would stop (similarly I found the base could collect a small amount to make you think the seal is leaking, though I see that isn't what the clip shows).
I also found it needed the two main housing clips to be forcefully pushed inwards to click in on
top of the motor housing, not just pushed in until it looks sealed.
For bubbles, I noticed the white plastic air scavenging pipe inside the top wasn't pointing right up - in other words it couldn't scavenge to the top of the internal cavity. That meant some residual air, which would occasionally burp. I spent some time gently shaking it every few minutes after each clean to dislodge any remaining air, and then it stayed silent(-ish).
@si walker, are you controlling only the outflow? If the inflow then the bubbling might be due to cavitation - I gather it is best not to restrict the input flow on these impellor pumps. I ended up making a clamp on the outflow pipe by cutting a bit of broom handle in half width-ways and clamping the hose between the two rounded sides using some bolts and wingnuts. Full flow to no flow very easily, no bubbling noises.