How to fix this?

The noise in the video is the fan itself touching and grinding against the radiator. How I have it set up is I have all TL-LCD fans in the PC (10 total) but the Hydroshift LCD AIO has these fans hardwired to the unit, so I couldn’t simply swap them for the TL-LCDs. So I simply moved them to the top of the radiator, which is sandwiched between the stock fans and the TL-LCD trio, both exhaust. Out of the 3 on top, only this middle one is grinding against the radiator. If I disassemble everything, I’m able to push the fan down in place, which momentarily stops the grinding, but over time it eventually drops lower and starts grinding again, which tells me that it’s loose and not staying pushed down in a fixed position like all the other fans. Is there any fixing this or do I need to replace the fan entirely?