HOB Protein Skimmer leaks at O-ring Collection Cup

[pjord500]

Have tried multiple attempts to put O-Ring (as well as layers of rubber bands) but unable to stop water leakage from coming up from the sides of the collection cup and dripping out. Would appreciate any tips or suggestions on this.

 

[pjord500]

It is a Aquamaxx 1.5 HOB protein skimmer by the way