Bonsour Tom,
I will try to answer your questions.
First, there are no more $200 to be won. Unless you happen to run across. One the cage got back for some reason. Or one was left laying around the cage. The maker has stopped making them.

The $200 strikes are won/gotten by playing the silverstrike machines. Till you have won/gotten 20 of the $10 strikes. Then you take these 20 $10 strikes to the cage. And exchange them for a $200. You donot get them directly out of the machine.
You cannot get a $200 by playing. The strike machine in just any of the casino's. You have to play the strike machine. At only the casino's that offer/has $200 strikes. Not all casino's has $200"s

The $200 are themed to the $10 strikes in the machine at that time. And to get a $200 of a certain theme. You have to turn in 20 $10's of the same theme. The $10 can be mixed ones of the same theme. On a rare occasion, that the casino. Is out of the themed $10's. For a certain theme $200. A casino MIGHT bend this rule. And you could get a $200, from a different theme. BUT, this is very rare!

The old and new machine difference. Is the design of the machine. And the way the silverstrikes are delivered to the player.

The old style machines (which are almost all gone). Look and operate a lot like a regular slot machine. The strike is dropped out of the strike machine into a hopper pan. At the bottom of the machine. They had 3 paylines, where you could win a strike. And it was possible to win from 1 to 5 strikes at one time.

The new style machines, are much fancier. And operate much the same. As a regular slot machine. But the silverstrikes, are delivered out of a revolving drum. At the top of the machine. When you hit the strike symble, on the 3ed reel. (There is only one pay line, on these machines). The drum revolves around, and stops. Then a strike is dropped out of the drum. You can win only one strike at a time on the new type machines.
I hope this pretty much answers your questions.
Dan