@fbz I have a Wurltizer Sillouhette, I bought it originally as a non worker at rock bottom junk price out of a secondhand shop with the intention of doing the same, but I have a bit of a mechanical habit too and I worked out how it worked and found the problems with some of the carousel mechanism that was causing it to not run (mostly bad limit switches and a cam had cracked and slipped causing the load arm not to home properly), and replaced some parts of the amp and made a replacement for the broken cam myself, now I can't bring myself to cut it apart.
Originally it had 4 panes to carry the jukebox title cards, but I've left out the center 2 to give me this window and kept them in a shed instead. I really like watching the mechanism load and flip 45's through the window created, its the most fantastic bit. Especially as I went through and fixed the lighting too, and I put a earth on and stopped the mild electrocutions caused by someone's previous repairs on the amp. Mostly the wrong volume pot, because the originals are expensive (like $50, for a variable resistor with two wafer layers...) but a odd pitch and layout. Needles and stuff are still available and I know audiophiles change them out for better sound.
It has a external input for the amp like a lot of commercial jukeboxes and remote controls via a wallbox feature so I might put a beaglebone on that wiring plug to simulate a wallbox and make it network aware for mp3's. There's a jukebox remote project on github.
It is awesome to have friends over, put it on freeplay and just watch it doing its thing and lighting the room up as people punch buttons into the selection computer.
I didn't have manuals for it at the time, its so simple and modular inside its not really needed and they were built to be serviced in the field so everything comes apart fairly easily, but I might have picked some service manuals up since I did it (its been a few years), I'll have a dig about.
There's a jukebox technical mailing list but it has hardly any traffic.
They're also fairly heavy because of the robust construction, and its too big to pass through the door of my (downstairs) office so I had to load it in through the window using a motorcycle lift as a lifting table. Once its in, its on castors and rolls out the way easy.
Would I recommend it, yes, and I'd try to base it round a older one if possible but in the transistor era unless you like the smell of dusty valves. Especially if you can get really lucky and find one that's not collection prices.
Maybe find one that is really really knackered inside so your not tempted to just restore it instead :)
I've attached some pics. I cant comment on alternative brands because I've only ever worked on mine but its probably a bit like arcade machines, made to service and well built to earn money.