Wet Appliance Floor Damage
The floor damage in the picture above was caused from the
wash machine hookups, leaking. The water worked its way underneath the
foot of the wash machine and flooring. I would imagine that over time,
the moisture worked its way into or behind the baseboard and then
underneath the linoleum floor.
Since the wash machine hadn't been moved in years, when it was time to move the wash machine, the linoleum must have stuck to the bottom of the wash machine and then separated from the damaged sub floor.
It's hard to tell by looking at the picture, how bad the subflooring is damaged. You could stick a sharp objects like an awl or a screwdriver into the flooring. If you can easily work one of these sharp objects into the flooring, you've got some pretty bad water damage.
If you can't easily push it an awl into the flooring, your subflooring is probably in good shape.