I was wondering if anyone had any insight on how to calibrate a particle counter without having someone else come in and do it for me. The company no longer provides service on it and others want $700 which is out of the (nonexistent) budget for my project. The particle counter is a Met One Model 2500 Automatic Batch Sampler with a Model LB1020 Liquidborne Particle Sensor. My advisor believes there is a dial/screw that can be adjusted to get the sensor calibrated but doesn't know where said dial/screw is located. Any insight would be appreciated.