ObservationPossible causesRecommended solutions Low event rateThreshold level is too highLower the threshold level PMT voltage for the threshold parameter is set too lowSet the PMT voltage higher for the threshold parameter Sample is not adequately mixedMix the sample to suspend the cells Sample is too dilutedConcentrate the sample. If the flow rate setting is not critical to the application, set the flow rate switch to MED or HI Sample injection tube is cloggedRemove the sample tube to allow backflushing. If the event rate is still erratic, clean the sample injection tube