At least on my antique bikes with 5-7 speeds in the rear
, it's easy to look down at the back of the cassette/freewheel and see if the chain is winding onto the sprocket straight-on, or off-center after a shift (having the bike on a repair stand makes it even easier.) You might try doing a shift on the floor, turning the crank a little to let it shift, and then inspect it to see. If you see more daylight between one side of the chain and the neighboring sprocket, that should help determine which way to adjust the trim to get things lined up and quiet again.
