Progress :- )
From the original pictures it looks like rust is the problem, but grime have much the same effect on the presser foot lift. Lots of links involved? Either way the solution the same; spray can stuff and oil. Some cases are more stubborn than others, but I guess you know everything about it. I had to oil for 4 days in a row to get a machine to free up completely, and it was just slow and sluggish to begin with.