I posted something incorrectly in regards to the Sunsun 302 above.
The primer button is indeed serviceable. I actually just discovered this a few days ago. To get at the innards of it, you have to pry off the textured blue cap on the button with a small flat head screw driver.
Once that is off, there are 4 philips head screws below. After you remove these screws the primer assembly and springs can be removed from the filter head. Low and behold there's yet another O-ring seal for the primer "piston". I've never seen this one talked about and I don't know of replacement O-rings for it. You'd have to find/fit one yourself.
Probably best not to use the primer. It did have some grease installed on it from the factory.
The primer button is indeed serviceable. I actually just discovered this a few days ago. To get at the innards of it, you have to pry off the textured blue cap on the button with a small flat head screw driver.
Once that is off, there are 4 philips head screws below. After you remove these screws the primer assembly and springs can be removed from the filter head. Low and behold there's yet another O-ring seal for the primer "piston". I've never seen this one talked about and I don't know of replacement O-rings for it. You'd have to find/fit one yourself.
Probably best not to use the primer. It did have some grease installed on it from the factory.