Jon I shamelessly borrowed your picture.
Good write-up but I'm a bit slow.
Are you saying the needle is bent?
A sudden higher voltage, than the scale can take, will do it.
Attachments
Bent Needle.jpg (47.2 KB, 191 downloads)

"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."