expanding foam gun problems

BluePlanet

I'm having a re occurring problem with expanding foam.
Using a gun.
First time I use a can everything works fine.
Next time I use it, say next day, or next week; only a tiny amount of stuff comes out of the gun, and there's only a small burst of pressure.
I can shake the can up for a few minutes, but it doesn't really make any difference.
I get one little squirt of stuff and nothing else. After the initial small burst of pressure I can pull the trigger again but nothing comes out.
I always use the cleaner, and keep the gun nozzle super clean.
It's recommended to keep the gun on the can between use, but after the 1st instance of this, I read that some people remove the gun from the can - this is a dangerous business because the contents are under pressure.
Nevertheless I have been doing this by placing can & gun into a bin bag and unscrewing the gun from the can while it's all contained inside the bag.
Then thoroughly clean both gun and top of can with the cleaner.
Initially this seemed to work but now it isn't working anymore and the same problem is happening.
Have replaced the gun 2x now, and have tried 3 different manufactures of expanding foam.

So maybe i'm doing it wrong?

Can is not empty either, I can tell by the weight of it and there's liquid sloshing around when shaking the can.

hesker

This is what works for me.

Remove gun from can and use the gun cleaner.

Despite how well I clean it there always seems to be a little residue that gums it up when stored.

So when I go to use it I dismantle it and I always find that the ball bearing is stuck. I squirt some cleaner into to it and work it until it frees up.

Works perfectly after that.

whizbang

Invert the can, leave it for a few mins till it settles, and then spray till it blows air before putting away.