Shelley,
I certainly wouldn't want to take the arm/pillar off. I'd be afraid all the other parts wouldn't go back together and have it work as well.
Do you have a scanner to get the front cover of the green manual. I'm curious as to which machine it is for. I thought the majority of them are 221-1. You might want to try
http://ismacs.net/singer_sewing_mach...s-200-299.html for the differences between the various sub-models. The other site listed above also has something about the difference in the face plates but those are easily switched. I think the badges and decals were changed a little bit, too. Maybe researching those may give a better time frame of your machine.
I like to think that most of the machines have original equipment and parts - I should know better
.
Janey -Neat people never make the exciting discoveries I do.