The only thing I would do is flush the lines well with fresh clean fluid using a pressure bleeder. If the lines are blocked internally then they should be replaced as they are likely rusting internally. Please don't misunderstand, I'm NOT saying the lines are rusted internally but if they are blocked THEN I'd be concerned that they are rusted.

Been wondering lately how you are doing on this project.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer