Bernard,
Your welcome, yes this a great site for users of all makes & softwares to work toward a common goal ! Less frustration hehe.
Call B & S or your local distributor. The people who calibrated the machine? Give them all the important info of make model serial ect. You should expect the accuracy from the factory spec. The Jay bro`s brought up some very good points to bear in mind.
jnlj@home.com