The locking knob on my Hayward C751 filter just spins when I turn it. I can't seem to unscrew it - at either the top or the bottom of the tie rod. I'm worn out trying. There's no pressure in the tank, and I've tried gently prying and coaxing with a rubber mallot. Any ideas?
Stuck Hayward Filter Head
- Thread starter bdavey
- Start date
- Jun 22, 2014
- 52,078
- Pool Size
- 17888
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
Welcome to the forum! 
Well, I "think" your C751 is similar to my C1200. When the knob just spins, it could be an indication that the locaking e-ring inside deteriorarted. Perhaps the knob can no longer grip the top of the rod in teh filter to lift itself off. The first time it happened to me, I got luck by lifting the upper half and turning the knob. Here is the link to my repair thread so you can get an idea on what's inside if you didn't already know: Hayward Cartridge Filter Locking Knob Repair. Maybe the images will give you an idea or two.
Well, I "think" your C751 is similar to my C1200. When the knob just spins, it could be an indication that the locaking e-ring inside deteriorarted. Perhaps the knob can no longer grip the top of the rod in teh filter to lift itself off. The first time it happened to me, I got luck by lifting the upper half and turning the knob. Here is the link to my repair thread so you can get an idea on what's inside if you didn't already know: Hayward Cartridge Filter Locking Knob Repair. Maybe the images will give you an idea or two.