I’ve kept the rubber plunger out of the tube when in storage. When kept inside the tube it compresses the rubber and retains the shape memory which causes it to fail. Haven’t ever replaced mine and it is eight years old. Still works perfectly.
My original one i had to do this but the one i have now, if you fully depress the plunger with no coffee in it it comes out the bottom just enough to not squeeze the sides.
Just push the piston all the way in, and the rubber clicks when it comes out the other end of the cylinder. This way you can store it in a compact package.
Interesting. I’m using the AP Go, so maybe the normal one doesn’t extend all the way through.
Edit: just checked how my normal AP works. It’s basically the same as the AP Go, but I guess this is a fairly new model, so there may have been some changes.
Are you using an older version?