If I remember correctly, There isn't one. There is just a sivle colored lever at teh back of the heel. You'll a knotched rail below it. Insert a hefty screwdriver, flat head type, under the lever and twist the scerwdriver. This lifts the lever up. while you hold it up move the heel forward or backward (you might have to bang it with the heel of your hand to get it to move at first.).
When you snap in your boot, the ears of the heel should come close but not touch the back of the boot, i.e. the heel portion. the ears will push down on the flat portion without touching the rest of the boot.
Why do you need to readjust this? Are you fitting the binding for someone else to ski it? If so, you'll have to redo the DIN settings. If you have time go to a shop. if not, email me with ther person's (or yours- whomever will be skiing these) with age, weight, height, skier I, II, or III, and boot sole length (printed on the side of most boots, a 3 digit number, down at the base of the heel on the inside, (that's between the feet). I'll send you the din settings, but when you hit the hill, drop by the shop up there and have them run an ASTM test. This will cost about $15 instead of $20 or $25.
BTW- 900S Salomon... very nice binding! Bob
Life's a pain... then you nap. Cat philosphy