Check the most recent lift test; if it is lower than -3 (say, -2.5), clean the top of the unit to see if the situation improves
Check to see if the ceramic tubes are touching the sides.When they rub, they cause the weight to appear to be jumping around and/or going backwards
Verify the filter temperature.Do this only after the unit has been heating up for more than 10 minutes.This can be done by turning the unit off, holding down the ‘7’ key, and turn the unit on. Hold down the ‘7’ until the red display lights up and check the numbers in the ‘chamber temp’ and the ‘percent loss’ windows.‘Percent loss’ should be the larger number.If it is not, replace the filter element—there are two filter elements, based on series. NC-1410 for the 1087/1275 series, and NC-1425 for the 859/945 series
