Poor Mariam! I do appreciate your sense of humor and hear the frustration behind it. It could have easily been me!
The last tensioner I took apart needed a better spring and I couldn't find one. I carefully recoiled the problem spring, and it took three days of off and on trying to get the tensioner back together. Now I take them apart only as a last resort.
This does give me an idea, though. We have universal thread cones that will work on most any machine. Why couldn't there be a tensioner that fit over or near the bad tensioner and could be used instead? If someone could manufacture those, they could make a lot of money. Another idea would be for a company to make a universal replacement tensioner.
I would use a vacuum cleaner with a small, long attachment. I wouldn't go for compressed air or I might have more frustration if a piece of metal got forced in somewhere. Or you could put some masking tape, rolled up like a lint roller, on the bottom of a straw or slender piece of wood or something and put it down there to pick up metal.