Oh also, the bass was made in 2012 and not 2004. I don't care either way, but what if any difference is there between basses in those years?
Oh great news! I was also wondering cause from the pictures in the classified it looks more "modern" than a 2004. They started adding Trussrod beginning of the 2000's so you have a more modern one that should be more durable in the future. I also believe the neck coating will stand better in the long run. (I have a fretless that spent 6 months this year to get the neck recoated, it is now absolutely perfect and feels like new but still).
If it was me i would also avoid sending it back to the ZON shop, they would definetly make it right for you but who knows how long it will take, my fretless recoating took a little bit less than 6 month, it was ok cause I did not really need it but that's a long period for a maintenance.
My recommendation is to find a trusted tech that is local to you, get the John East (if the size match of course) and give it a shot, you will immediately see if it's working for you without the hassle of the wait time and the shipping cost (back and forth).
The polyfusion is nice, very musical, but for a me a quality preamp is a quality preamp
A more standard preamp that any good tech can service is the right move for an instrument that should serves you well for year!