the way I always used to adjust mine was to take a metric ruler, and measure from the bottom perch to the bottom of the locking washer/perches (the things you spin together that the springs sit on). I'd pick a starting point on one, and take note of the measurement. Then apply the same one to all the others. It might take an adjustment or two.. im sure you'll figure out the height you want. good luck. Also a string and a marker work too.