Welshweeks
Fishaholic
I don't think the temperature gauge on your heater being a little off indicates that it's faulty at all. From what I understand it's pretty standard for them to be a little inaccurate. Just use your tank thermometer as a guide and set the heater appropriately.
I don't think is faulty, really more a case of I cannot use the scale on the heater to accurately set the heat and as you've stated I do indeed use the glass thermometer. I just think that if the other heater has a accurate digital display built in I would personally prefer that as it's less hit & miss then adjusting my current heater and then waiting to see what the temp changes to on the glass thermometer!