Looking for assistance on identifying Parker SBT

[Phil Reiser]

I am located in Canada and am in the process of assisting a Late Friend's son in liquidating his Fathers gun collection. One of the firearms is a Parker Bros SBT 12 Gauge Serial # 178218 with 32" barrel. I have identified that this firearm was manufactured in 1917 but have not confirmed much else about it. The grade is not marked on the water table above the serial number. The frame size on the barrel lug shows a 12. Is it common for the / to be missing between the 1 and 2 which would then correspond with the chart in the Technical Information on Parkerguns.org. At some time in its life it has had a Morgan Premium Adjustable Curved Recoil Pad installed. There is a crack that has been repaired at the bottom of the forearm. I also suspect the wood has been refinished.
Any information anyone can provide based on the accompanying pictures and info I have provided would be greatly appreciated. An educated guess as to its value would also help me in pricing this item for sale.
Thanks,
Phil