Lack Of Air To One Side Of Tub, Weak Everywhere

[greenworks]

Fellas I have had air injection problem as of late, when I bought the tub used I had one side of the tub not working the warrnaty on it came in and the repair guy came out cleaned and lubed the jets etc and over a period of three days the jets came alive. So much that it will hurt your back with air for over a month, then the last couple of days I lost one side of the tub again. The repair guy blew compressed air from my shop into the air intakes would there be some scale or deposits in the air lines causing this blockage if so are there things that can clean a spa of these with out dumping water as we are still pretty cold up here to be draining water.Exactly how does the jet inject the air if you pull the jet out you get no air with the jet in(the ones that work) you get air so it must be something the jet is doing. The tub is a beachcomer tub.