If your D25 is drifting or is not reading accurately, perform the steps below to attempt to diagnose and/or correct the problem.
Run the instrument diagnostics as described here. Perform any corrective actions required by these instructions.
Replace the lamp as described here.
Clean the system as described here.
If readings are still unsatisfactory after following these instructions, instrument service may be required.
Information about how the DP-9000 carries out the averaging operation can be found here. You may want to read this information if you have concerns about "rounding error" in averaged measurements or if the values for the individual measurements do not seem to yield the averaged values.
To read Six Things You Can Do to Help Your Instrument Perform at Its Best, click here.
If additional assistance is required, you may contact HunterLab.