Well, you have two possiblities that is causing a weak signal. the dish elevation is incorrect, either to high or to low. A quick check to verify which way its off is by pulling gently down on the dish while watching the signal levels then adjust the dish accordingly.(towards the direction that gives the best signal) The other possibility is the azmuith is off, which is left to right movements. A quick check is using the fine tuning menu in the receivers menu positioner settings / USALS.