The leak occurs only when I adjust the airflow to the jets. The tub is approximately 7-10 years old and im finding some black o-ring material in the bottom of the tub on occasionally.

The flow controls on several of the jets dont work and/or are very difficult to adjust.

Could this not be a manifold problem and more a problem at jets that are deteriorated?

If it is jet issues. How do I remove and replace gaskets/o-rings? I believe they are waterway components.

sounds to me like you have the cause of the problem at your grasp... the o ring material is most likely from dried up o rings that seal your manifolds and controls to prevent water from excaping. In most cases you can, with a bit of work, replace these o rings.... sometimes a whole body replacement is necessary... it depends on the type of manifold and controls you have.