actually don't be confused what you were told but either side can be out sync with the small gear in relation to the large gear on the throttle piece. there is usually a purple line on both small gear and large gear and at the point both purple lines, line up the throttle should be entirely closed ! I would check with the top cover off and with both throttles fully closed turn the power off and then on if your red light comes on and stays on then your adjustment could be off! when both throttle are closed are they lined up at the same throttle setting. in the front of the transformer, another words both throttle should be at the same exact height when the throttles are closed ! if one is higher then the other then the higher one is off probably because one of the gears slipped past the other gears and that's the one that need adjustment!
p.s. if you look at the left side of one of your pictures you will see 2 purple arrows they should align up when the throttles are fully closed ! compare one side to the other and you will see what I'm talking about! p.s. sent you email!!
Alan