Pro Clear 75 issue

Bought this system used and its an older version of the 75 compared to whats available today.
Heres whats going on and I can not seem to figure out how to solve this problem and this is my first time with this type of filter set up.

It is an overflow system predrilled. There is a bulb/float in the overflow which is for some type of regulation I believe. It is gravity fed into the filter system.

The float tends to bob up and down real hard every few minutes, kind of a\ gasping for air type thing. In this occuring the cap over the drip plate rises and falls and water comes up over the cover and leaking over the sides. I am missing something, whether it be a part or the know how, but any help would be greatly appreciated.
thank you
terry

 

can we get a pic

 

Sounds like some kind of wave generation device, or even possibly the start of an algae scrubber type of idea. I agree we need pics.