If you find it annoying to have to dispose of a device because some part is broken and spares are either unavailable or cost more than replacing the device as a whole, we have something in common.

Some years after I purchased and installed soaker hoses in my garden, one of them started losing just as much water as the small vent on its pressure limiter allowed, springkling a small area generously while no longer dripping along the hose's length.

It turns out that this type of pressure limiter can easily be taken apart by unscrewing the hose connector from the rest using a spanner/wrench or pliers, removing the gasket and the flow limiter insert and unscrewing the cap using a durable object of suitable size and shape (I succeeded jamming combinations pliers into the lid).
Once the lid is off, the innerds can be pulled out easily. Note that the cap contains an o-ring.
After cleaning, widening the shrunk piston and greasing it up with silicone grease, erything has to be reassemble