I am an R/C tech with experience with Ace products, and may be able to resuscitate your DDVC. I have an schematic for it, as well as for most Ace items.
However, there is no guarantee. The DDVC is based on a micro-processor, the heart of all computerized equipment. Due to the age, I doubt if the one used is still available. Even if a new one is located, they have to be programmed for a specific use and that info is not available. It is possible that Ace purchased them in batches, and had them programmed by another company.
The same applies to the digital display. If it is dead, an exact replacement is probably not available.
Of course I can't say anything definite without testing it. If you want to gamble the postage, fine, though maybe you will run into someone closer - I am in CA!
Eloy Marez, 2626 W. Northwood., Santa Ana CA 92704.