Using the carriage or tailstock to measure for wear on the bed is possibly confusing the issue(s). If the wear is localized, both the carriage and tailstocks could be 'pitching forward' when they enter the worn section. Etc.
Why not use a straight edge to directly check the straightness of the bed [1]? Given the big misalignment between the centers, I would guess that deviations should be easy to see.
BTW, do you know anything about the history of the machine? If it was used in a production environment doing the same operation repeatedly, virtually all the wear could be localized to a pretty small section of the bed.
I think wear just seems to be a more likely answer rather than the bed being bent. The link Tom Kitta supplied suggests that the ways were made of hardened steel. It is hard to imagine them sagging--especially to the magnitude shown. Unless, of course, some previous user was slamming down 1,000 pound loads directly onto the bed?!?
Craig
[1] Lee Valley has an inexpensive line of straightedges that would be accurate enough for this job:
https://www.leevalley.com/en-ca/sho...d-measuring/56676-veritas-steel-straightedges
