How tall is the tank and how far below the tank are you?
What has happend to myself and friends of mine is that the FX5 pump is in the bottom and sometimes debris, snails, and whatnot get in there a plug up the pump.
I would take my hoses off and blast them outside with the waterhose to make sure that there is not a problem with plugs in the line.
Also, how far into the water is the output nozzles? If I am not mistaken I think the manual lists a specific height not to excede below the water line.
If anything is wrong, I would be more concerned that your lid expanded like that would suck air into the system and wrecking your siphon flow. IF your canister is not filled completely with water this is going to effect your pump performance which would reduce the output flow and pressure.
I would take the filter lid off clean it, and then retighten in a even criss-cross sequennce. Never tighten the knobs with a handtool, always use your finger tight. If the canister lid bows or leaks, then you will have to go get a new case o-ring.
Just re-looking at your photos and the hose on the right is dipped below the canister lid. Which hose is that? suction or discharge?
You do not want to make any drip legs because it also ruins your siphon effeciency. You need to trim your suction and discharge hoses so that they are as near straight as possible to prevent flow losses.
Re-evaluate your hose locations. Look again at the DVD movie or in the manual and make sure your hoses are at the minimum or under maximum heights listed.
Hope this helps...