Boys and girls.....In Kubota service school, they expose to leave the filter alone - do not remove, replace, or clean. As there is a decent chance of not getting a good seal and dusting the engine.
They expose to leave the filter in place until airflow is extremely restricted (black smoke in exhaust) and then to replace with a new one using grease to aide sealing (OE of course - if your tractor is under warantee only use OE as Kubota is extremely hard over on this).