Take the chainring off and place on a a sheet of paper.
Mark the outline and the inside of the arms. Rotate the chainring around one arm at a time and see if at any point the outline doens't match up. If so, it's out of round and the cause of your problems.
Take the chainring off and place on a a sheet of paper.
Mark the outline and the inside of the arms. Rotate the chainring around one arm at a time and see if at any point the outline doens't match up. If so, it's out of round and the cause of your problems.