I don't know if this has been discussed since, but the "fix" from the link (ie. drilling holes) is not a good idea. The "swirl" pot does indeed get filled by a venturi effect from the fuel return and drilling holes will only allow the fuel to be at the same level as what remains in the tank. If the swirl pot is not staying full it can only be down to 3 things. An obstruction in the return (unlikely), a leak in the swirl pot or most likely, foreign matter in the tank affecting the venturi (I have found this on a Vectra before).
With regard as to whether your pump is on the way out or not, do you have access to a scope and a low amps clamp? Just reading current on a DMM will not give you the full picture. This explains it better than I can as I am not an electrician.
http://www.picoauto.com/tutorials/fuel-injection.html
HTH's
Bryan with a Y
PS. Just thought that if the pump efficiency is bad, that would perhaps be a fourth reason why the swirl pot wouldn't stay full.