Yes change the lines and the check valve at the tank pickup. Use good fuel line. If you ended up with the primer ball being sucked down that sounds more like a fuel line clog, not a leak letting air in.
A couple things to check, somewhere between the primer ball and the fuel tank the fuel line could have gotten so soft internally that it was collapsing as the pump is sucking fuel.
Or the check valve at the tank pickup has corroded, stuck partially closed and blocked flow.
I've experienced both of these and they showed up as the primer ball being squeezed down.
