That was a sweet present, enjoy it.
According to the ISMACS chart that serial number dates it to 1894.
I would clean it with sewing machine oil and cotton balls before using car wax on it. And do not use anything with any form of abrasives or harsh chemicals in it. Your decals will die a horrible death if you do. Stay away from Simple Green and other cleaners of the like.
If it has Sphinx decals it's most likely a Model 27 or 127. I could be wrong ( hope not) but I've read that only the 15s and 127s used the Spinx decals.
I'd contact forum member Glenn for any questions on refurbishing the head and treadle base.
Here is his tutes on those: {
http://www.quiltingboard.com/vintage...s-t186522.html }
and
{
http://www.quiltingboard.com/vintage...ts-t97670.html }
Read and ask questions before doing anything on something this precious.
Joe