Just an update on my leaking sunsun. I did some more experimentation on it given I haven't received the new O-rings yet. I ran it without the media baskets. Still leaked into the space in the top. I took the top apart which was real easy, by removing 6 screws and it appears to be leaking from the primer button, which best I can tell, is not serviceable in any way?
Since I've had this canister for just under a year (mail ordered it late Dec 2016), I emailed the eBay seller- cll_petsupplies. They basically told me to get bent. "Sorry, we have never encountered this issue." I've bought lots of stuff from this seller over the years. They are cheap and fast. Just don't expect much down the road from them. It's not the end of the world since this unit was $41.88 shipped, just ticks me off because I have another 302 that's been running for 5x as long and it's on all original parts, seals, etc! Canisters sure are awesome until they're not and leak all over the place. Ugh.