So this is an add on damper from Tama, probably. Those are interesting dampers because ,when they work well , they combine the features of an adjustable and a quick on damper. Unfortunately, I think it will detract from the value of your drum. The drum has ,intrinsic vintage value as an original drum but if there have been new holes drilled to accomodate the damper( for sure), then it has been altered---which isn't good.
These are really good drums. They have cast hoops and a really great tone if headed properly and set up with the right wires. Have you considered keeping it as a player?----and building a kit around it?
I don't think it's worth much more than 150.00 local or 100.00 as a shipped drum. That's if everything else is o.k.