The finish looks to be redone, other than that it looks decent.
When you say that not all of the "selection buttons" work that could mean a few different things. Anything from the Electrical Selctor (Selection Buttons) being bad meaning a dirty or misaligned contact or broken wire. Next down the line is the actual cable itself that terminates at the Selection Reciever via a Cinch Plug (AKA: Jones Plug") Sometimes there are pinched or broken wires in the bundle or a dirty plug blade/socket.
The next most likely canidate to cause a problem like that is the Pinbank. The Pinbank is comprised of a bunch of coils and levers that correlate directly to the selection made on the Electrical Selector. After almost 60 years of work and abuse they always need a good cleaning. Checking these things will more than likely solve the problem. Overall, pretty cheap to fix. You just need to invest some "sweat equity"!
The amp on the "B" is really durable. Have all of the capacitors replaced regardless of age unless it was recently recapped. Also, check all resistors to make sure that they are within tolerance. You also want to replace the Selenium Rectifier. If you turn the amp over, you will see a component that looks like a stack of rectangular metal squares with a couple of wires connected to it. The Selenium Rectifier converts AC power to DC power. When they get old they either outright fail or they start to get flakey. By flake I mean that when you test it by itself it seems fine but when it's under a load, your jukebox playing, it takes a crap on you. They are cheap to replace at around $5 and are available at Radio Shack as a "Full Wave Bridge Rectifer" they even have a hole in the center to facilitate chassis mounting just like the original.
It's always good to have somebody that knows these amps to do the work if you aren't to sure about doing it yourself. The amp in my "B" worked ok when I got it prior to restoration. It was only later and through another set of eyes that I found out that my amp had been partially updated to a newer revision. When I say partially I mean that the tech who was doing the work didn't finish the job. I recapped my entire amp and also replaced the caps on my Selection Reciver to include the Cancel Credit Unit (CCU). Make sure to clean the contacts as well.
Try to get it for less by citing the work it will take to track down the selection problem plus how much it will cost to re-cap it to make it safe to play.
Good luck and let us know how it goes! (Try $725!!)