It looks like the multiport isn’t seating because something’s keeping the stem from dropping back into place. A couple things to check before forcing it:
1. Make sure the spider gasket is lined up.
If it shifted when you pulled the valve up, it can stop the whole assembly from sitting flat. Even a small misalignment can keep the collar from fitting back on.
2. Check that no sand got onto the lip of the opening.
If a bit of sand or debris is sitting on the rim where the multiport sits, it’ll keep it from dropping all the way down. A quick wipe around the edge usually fixes it.
3. The standpipe inside the filter needs to be centered.
Sometimes when you lift the valve, the standpipe leans slightly. If the multiport isn’t sliding cleanly onto the standpipe, it’ll feel like it won’t push down. Gently wiggle the valve while lowering it to help it seat.
4. Don’t use brute force.
You shouldn’t have to really muscle it. If it’s not going down with steady, even pressure, something’s misaligned.
A light twist or wiggle while lowering usually does the trick. Once it drops onto the standpipe and sits flush, the collar should slide back on normally.
Let us know if the standpipe looks straight or if the gasket shifted, that’s the most common culprit when the valve won’t push back down.
