I recently purchased a typewriter from a thrift store which appears to be in good working condition and as it's my first of this age (I believe from serial number dating it may be from 1931-32) I have some questions about it and was hoping to find some answers/guidance here.

Im assuming from the look of it and the age that it may be a Royal 10, but all of those I have seen pictures of are completely black and mine has a crackly gray top with black back/sides.  Im wondering if this has been refurbished?  Has anyone seen anything like this?  (Just realized I have to post twice to include pics)

Im wanting to give this a solid cleaning.  I removed the cover on the bottom and gingerly cleaned inside with a brush and the vacuum.  It didnt remove any build up but it certainly got a lot of dust and cobwebs out.  The rest of the machine, particularly the outer exposed metal parts (please forgive my lack of knowledge of these part names - Im learning!) could use a good scrubbing.  Im still doing research on the best method/materials for this but it seems some websites are in conflict with one another a bit. What would be best to clean the metal part of the paper holder and the margin stop bar?  Nooks and crannies around/on the various levers?  

And also - I was looking at a manual for a Royal 10 and cant seem to figure out what the name or purpose of this bar I have attached to the margin stop bar is for.  Im including a photo of it for reference.  Any ideas what this does? I Assume it has something to do with margin guides??

Thanks in advance for any/all ideas.  This is a beautiful machine and I am really excited to get it cleaned up some more!