Main fuel filter pop out / NEED TO BE TESTED AT EACH ANNUAL OR FUEL FIlTER CLEANING

I did a inspection on a Fouga and this is the indication that the main fuel filter was contaminated

The pop out did his job.
THE POP OUT NEED TO BE TESTED AT EACH ANNUAL AND FUEL FILTER CLEANING
If the pop out does not pop out when you push on it from the inside, if your fuel filter get clogged,
the fuel will not be able to bypass the main fuel filter and fuel flow will stop going to the engines and you will have engines shut down due to fuel starvation. 
Be careful that before installing the new filter or clean stainless filter, that the bypass pop out is working and free to pop out and to be reset because some 5606 oil can drop on it (because the hydraulic reservoir is just on the top of it ) and with time the oil dries and become like sticky glue,  that will prevent the pop out to function normally so no way to see if the filter was bypassed or not.

Old paper filter and new stainless fuel filter

After replacing the main fuel filter ( paper filter cannot be cleaned ) everything is
back to normal and pop out retracted

For your information the fuel filter pop out need to be checked every flight by the pilot.