skimmer filtration

I've recently bought a deltec mce 600 ps off ebay and have noticed that its not been skimming like it sould. Ive taken the pump apart and have noticed its not a pinwheel design but a standerd impeller wit holes and grooves in it. i have also noticed that the flap on the outlet is entirely not...

just wondering if anyone has seen these or seen them in use or anything.... im trying to find a nice filter to use on my new 40g setup...... i know sumps are better but no room for one and wont really need one on it anyways..... its a 40g AGA, 175w mh 15k setup, 40lb ocean direct live...