As you may know and experienced, OEM parts and service kits for Dacor regulators have been discontinued since the brand was killed off years ago. You are not the first diver to experience the frustration of not being able to get their Dacor regulator set shop serviced and usable again. There are a fair number of shops (maybe all) that due to liability issues will only use official OEM service kits when servicing a regulator and given Dacor's status those kits are not available.
That being said, there is a following for Dacor regulators. There are folks that collect to refurb and use, and there are folks that collect them as interesting paperweights/bookshelf conversation starters. The ones that refurb and use them will almost always service the regset themselves or have an associate willing to do the work with generic replacement parts they have researched to know will fit.
My recommendation to you, if you are not willing to get involved in servicing your reg-set yourself is to put it for sale in the appropriate ScubaBoard classifieds section. If it doesn't sell quickly then just slowly reduce the price of the advertisement until you find the price someone is willing to pay. In the interim, start scoping out a new reg set or a used one of a brand that is still shop serviceable.
Good luck.
-Z