RICO VACS - is the schematic available anywhere?

I liked the subtle ticking noise of ye olde RICO VACS vario I had in the HP-14. And it was very good at pointing out weak lift. Alas that relic from the 1970s stopped working some time circa 2000. I sent it to its maker and he fixed it, but it later failed again, as has another unit I scrounged somewhere. So I have two of those sitting on the shelf. I'd love to get the schematic and try and revive it. Or build an equivalent audio-only unit. Is it possible to get the schematic diagram somewhere?