I have the manual and sent it along with my pump to have it calibrated.

Anyone who monkeyed with it probably is more liable for interfering with the proper operation of a device. These things have to be adjusted on a bench with specific readings. It cannot be adjusted "in the truck"

This is a multi-hundred dollar operation and you need to sue to recover your expenses. I do not belive any law requries someone to mal-adjust a complex device. And anytime you adjust a device without specs or proper procedure, you just MAL-ADJUSTED it by definition.