I'm going to assume your 553 is similar to my 555. I'm going to quote straight out of my manual. "The proper way to insure all excessive slack is removed is to lift all four wheels off the ground. Rotate the wheels in opposite directions until the chain is tight while holding the rear wheel stationary. Rotate the front wheel to determine the chain slack. This chain slack should be checked at four different positions by rotating the wheels and checking slack at 0, 90, 180, and 270 degrees to find the postion with the least amount of slack. At the tightest point, the front wheel should rotate 1/4 inch or less with the rear wheel held stationary." As far as adjusting, just loosen the plate on top of the chain cases and tighten her up to specs! (1/4 inch or less) I hope this helps ya!
