Skip- I have a first or second model Avocet 15 / 20, black with chrome. Fully functioning, original sensor + wire. I can send you the instructions in PDF. These do consume batteries but replacement packs are super cheap from Harbor Freight. I forget what the cross ref. replacement battery but it's just a simple match the diameter and voltage. Charming retro, kind of like having a first gen IBM PC jr. or Mac.

Yours if you'd like it.

Also, I know you picked up another Trek project. If you'd like, I also have a first gen Trek computer (believe it functions exactly as the above mentioned Avocet). Fully operating with sensor and original wire.

I'm really rewinding. Just installed a mechanical / o-ring drive Huret odometer on my Trek. LOL