Penn plax cascade 500 leaking

[manban]

Someone please help me figure out why my filter is leaking. I’m new to aquariums and I thought maybe I put too much water in the filter, but once I turn it on it leaks from the large clasps. The gasket doesn’t look broken or anything, I got it from someone on fb marketplace. I think I’m missing a part to it after trying to find out why it’s leaking, do the 500’s have the top little grate thing? When I turn it off it still leaks so I’m at a loss and just want some fish:/ (the water is coming from that little hole next to the clasp thing)

 

[Andy Sager]

Here's a list of all the parts your filter should have. See if you are missing anything which is why it's leaking OR that you have it set up properly. https://www.pennplax.com/_files/ugd/7fbf19_ef075ba51b024a88bfac18cffd71a431.pdf

 

[Aiken Drum]

Is it a new unit or a used unit?