I bought a house with a toilet dated June 1960 and having a Briggs imprint but no other information. Research on the net leads me to believe it's a Briggs Case 1000. The fill valve has an extremely slow leak into the tank, and the entire flush process is sometimes tempermental, all of which leads me to think a complete replacement of flush parts is in order. Local plumbing suppliers and plumbers are unable to help. I'm willing to make the repairs myself but I'm unsure of the exact model number for the required parts. The picture on the net of Case #5150 fill valve assembly for a Case 1000 is very similar but not identical to the one in my tank, although it may be the correct one. Question: how can I tell without error what Case model toilet I have and the appropriate filll valve replacement part number?