Fuel doesn't flow into Carbs..

[Masterflies]

Hi! Dear gurus, need your advice. Probably it's something simple, but maybe not )

After some period of inactivity (was transferring my GS500 to another country due to my relocation), when I try to start it, looks like fuel doesn't flow into carbs. Plugs are fully dry. Battery is full. I have a fuel filter, and usually it can be seen how the fuel flows, but now, even when I put fuel petcock into PRI, there are no movements in the filter:


Petcock is OK, fuel goes into it 100%. May it be something on Carb side? Any suggestions? Thank you!!!

[The Buddha]

Open the drain screws in the bottom of the carbs. The fuel should flow out, and it should be clean and clear, in fact drain it into a cup and get rid of it and start with fresh new fuel.
Cool.
Buddha.

[Manowar1313]

Does that fuel filter look backwards?