'37 Buick trans tower repair

[Wogden]

I have a '37 6 bolt shifter tower in for repair and have found that the conical spring in the tower shifter is broken and sloppy. Several questions regarding this repair:

Does anyone know of a source to repair this item. I am told that it takes a special tool to put it back together.?????

Has anyone found a souirce for the spring replacement?

Do you normally drill out the two rivets or just grind them smooth and then weld them on reinstall? 

Is there a replacement for the cork gasket that resides under the shifter cap?

 

Any info would be greatly appreciated.