ditto on the above... I put some thinner of whatever flavor in the cup and let it sit a bit to soak in (a few minutes at best) then out comes my handy Qtip soaked in my favorite thinner... I wipe it down real good inside, twirl the Qtip on the bottom to get the ring at the bottom then on to step 2...
I have some automotive style paper towels.. "Job Squad" at the grocerystore work good too... I roll the tip into a point place it in the cup and start twisting... I push more and more down till I am sure 90% of the paint is out and at that time the other clean end of the paper towel with some thinner on it gets up the rest...
lastly a pipe cleaner (available at Wlagreens and other chain drug stores) dipped in thinner gets the pickup tube clean... WALLA! perfectly clean...
personally I bought another cup for my 155 as it is easier to let one soak while I am spray cleaning the brush with the other... then I put my attention on the cup with the paint and 5 minutes later I am done!!