I have a 90s vintage Weber Spirit grill that was given to me a few years ago, with a full tank, with the old-style spring-loaded quick connect fitting. It was only last summer that I had to change the tank connection over to the screw type fitting. The thing is built like a tank, and, amazingly, parts are still available if needed. Plus one for Weber!
If you think you have a leak somewhere, slather some soapy water on everything. If the leak is at a fitting, tighten it a bit (they are usually tapered fittings), or disconnect and put some thread dope on that bitch!