Family Secretary desk

This piece belonged to my mom's great aunt and now i have made it a new addition to my home. I'm trying to date how old it may be and even who manafactured it. The dimensions are 41" wide x 63" tall x 16" deep. It doesn't appear to have dove tail joints as you can see in the attached photos. It does have solid wood slats for the backing. It also has wood wheels. The screws are standard and the hardware appears to be brass and is nonmagnetic. I found a partial tag made of a fabric nailed to the back that says the words W. C. Buch... then it's tore off. Below that it says Siou... and is tore off as well. The top of the desk appeared to overhang at the ends at one time but it appears to be cut off. It also has two 1/4" holes and some 4" markings on the top as if there was a piece on the top. I would love to know what it use to look like. I was also like to know with a old piece like this should it be left as is or can it be repaired and refinished?