MSR whisperlite fuel leak

I have an old msr whisperlite stove. On a recent walk down Hinchinbrook Island it developed a fuel leak which I cannot readily fix. The fuel appears to be leaking at the junction of line and pump. Therefore around the fuel line insert. I can see no obvious damage and from memory there is no O-ring here; just the black plastic sleeve which doesn't seem to be a replaceable part. Anyone have any ideas?