Micropipettes require routine calibration in order to give us accurate measure when performing experiments.
For the calibration, contact following calibration services
Pipette Calibration Services
831 Beacon Street, Suite 326
Newton, MA 02459
1-866-964-0039
Give them the address and other contact info.
Make sure you ask for 'onsite' calibration.
The charge is about $20 per single-channel pipette.