Mechanical Agitation - Round 1

I have a multi-stage plan for getting the gunk and the rust out of the tank. In step 1 I was primarily concerned with getting out the old fuel. I used a couple of cups of acetone as well as a handful of ball-bearings. I was careful to count the ball bearings before adding them to the tank so that I could later be sure that I had removed them all. Here they are, all 18 of them.

I let the acetone soak for a while, with the tank sitting on each side. Then I agitated the tank by manually shaking it. Then I dumped the acetone into a container, through a screen to capture the bearings. I counted the bearings, beginning with zero, until I reached ... zero. None of them came out. They are all still trapped in the gunk and debris. Clearly more cleanings are required.