To adjust the tracks, drive the vehicle onto hard solid ground. Engage reverse gear, release the steering lever for the track that is to be adjusted. Gently accelerate engine, as soon as the vehicle starts to turn, decelerate and reapply the steering lever to stop the sprocket being turned forward by the track resetting. The top of the track should have 1 to 1.5 inch sag between the guide rollers with no slack under the sprocket or rear (track adjusting) wheel. As has been pointed out to me, that's about the same as a fist-width between the top of the track and the hull.
The track pins are 9/16 UNF thread, I'm not sure about the track pads but will check later.
Andy