[Canadian Man]

I wouldnt knock out the teeth unless they are quite thin. The dremmel would be a better option, just make all the slots a little wider and that should make alot of diffrence.

Some options that i have seen is to have the top of the overflow below the water level and then use egg crate as the teeth. It allows most thing to not get sucked down and lets alot of water flow through.

When I install my bulk head i usually put some silicone on the inside part just to be safe. If you did over tighten the bulk head the rubber ring can bind and kink which will cause the leak.

In your situation I would either remove the bulk head and re install if it is convenient or.
Go to HD or REVY and pick up some GOOP or MARINE GOOP and apply that where the leak is and it will be fixed. Great Stuff!

Hope this helps.