I would call the Better Business Bureau, your State Attorney General and see if there is a complaint resolution segment on your television or newspaper (great suggestion!). I think I would try the TV/news first. Dealers need good reputations and a local story about a problem with them would make them think differently.
They have all the power right now and they know it. You have several tools - corporate, legal and reputational. I would use them all. I might consult an attorney to know what my options are. Two bad products, deprivation of the product for a prolonged period and the inability to get your money back might be grounds for a letter from an attorney.
Call Juki and talk to someone senior and ask them to "help with your dealer before you make this story public". They won't want bad publicity either. Keep being the squeaky wheel. If you go away quietly, you let them forget about you.
Good luck. Sounds like this dealer has lost your trust and you don't want to have to continue your interactions into the future.