Hobart Scale Calibration ?

[Bob]

A friend of mine is trying to find out how to calibrate her Hobart
Digital scale. Here are the specs.

Model # 1840-M Capy- 30 #
Serial # 13-355-151
Volts 115 Wattts 46
Amp, .4 Hz 60 MD CE

Any help on how this is done would be really, really appreciated,
because the machine would cost more than $5k to replace.

thanks,

Bob