Looks like all the stuff that required Java has been removed...
I think this probably has to do with the fact that as of FireFox version 52 (released in March, 2017), Mozilla has completely removed support for the Java Plug-in. In fact all plug-ins using the NPAPI plug-in interface are no longer supported with one exception: Adobe Flash (see here
for more info). So any site that uses Java Applets (like Bruce's) are effectively broken with FireFox 52 or later. (Note, if you are running the "Enterprise" ESR versions of Firefox, Java support is still enabled, at least for now. But Mozilla is strongly encouraging developers who have built web sites using Java applets to switch to newer more secure technologies).
In theory you should be able to use a different browser (e.g. Internet Explorer which still supports the Java plug-in) to access the web archive pages, however I just tried that with no success. The java applet starts to load but then reports "Class not found exception" for any of the calculators that are built using a Java applet. So in this case it seems even the web archive pages won't help. I suspect the web archive does not include all the files necessary to support the Java applets.
We can only hope that Bruce will consider updating the calculators to newer web technology to make them available again.