What gave you the idea that this beautiful gun was ugly ?
A good soaking with Secret Sauce may be all she needs ...
Why not just replace the pump cup and see if that fixes the pumping problem? Sometimes thats all that is needed, don't tear into the valve too unless you really need to. Just a thought.
Pump it several times and leave it over night. See if that air is still in there. If not you know the valve guys needs to be changed. Specifically the valve stem.