the reason I started thinking of getting rid of PPC was because of how difficult it is to work with my local dealer we have used 20+ years.
If your regular garage start giving you the run-around, will you sell your truck and look to a bike? Probably not.
Time to find a new vendor. You had a golden opportunity to do this before going alone and sourcing that C6100.
Your chosen vendor would have sold you a refurb color press for more than the one you found one on Craigslist or wherever.
However, it would be complete with controller, the vendor would have the machine at their workshop and replace/service whatever they needed to in order to bring it up to a standard that they were happy to put it on contract, before delivering and commissioning it.
The difficulty I expect you'll find going forward is, being offered an inflated PPC rate, to underwrite the unknown risk for a vendor in taking on the machine 'as is'. Or you may be offered a more reasonable PPC subject to inspection and spending several thousand dollars as a one-off, to bring the machine to a standard. If you're offered the latter, bite their hand off for it. Or better still, resell it on Craigslist for what you paid or thereabouts and then do what I've suggested above.