I have the following Schwinn bike pump. It’s pretty old, perhaps 30 years or more. I like it a lot.
Some years ago, I changed to Presta valves; for this I needed a new head. I got a Topeak SmartHead Bicycle Floor Pump Upgrade Kit, which is a replacement head and hose with a number of different adapters. Unfortunately, none of them fit this pump, so I just hacked off most of the worn-out stock hose and spliced in the Topeak hose (one of the adapters is designed for this).
Every so often, the splice begins to leak because the stock hose cracks a little. This is easily repaired by cutting off another 5mm and re-splicing, but obviously that's not sustainable.
Here are some close-up views of the threads, and also the gauge for ID purposes. That's a AAA battery for scale.
My question is: where can I find something that will screw into the threads in the base of the pump and somehow lead to a modern Presta pump head?