The paintwork looks good Geo.
I'm not that familiar with the hose and attachment sizes for the Testors/Aztec equipment, but if it's the 'standard' size of braided hose used on the majority of airbrushes and compressors, then I probably have a spare hose I can send you if you're stuck - should take about 7 to 9 days to get to you.
Once a hose has split like that, it can rarely be properly repaired, although a temporary 'jury rig' with gaffer tape might get you by for a short period.
As Wojtek suggested, it's easier, and better, to cut the hose and re-fit the union, or just get a new hose.