Hello @gmddl3,
I reattached the missing point cache files here, but you could just re-export from the included 3dsmax file to re-create them. It's a proof of concept so I spent 0 time trying to make it look good, the file is just to prove it works. Honestly, the way you have this setup there's not much point in using the linked xform. It's just acting like a bone without the control of a bone.
You have some work to do to fix up your rig and hierarchy structure before it's really stable. I'm sure you had some weird issues making some of these expressions. You have scaled bones and scaled parts parented to them at different ratios which will always lead to problems exporting with skin, so solving your point cache problem exposes other problems from a rig -> export perspective. You might want to check out some tutorials on rigging vehicles, I think you could benefit from them. Before you get export proper animation you need a properly setup rig, and xforms at 100%.
I went ahead and reset your xforms and rescaled or replaced your helpers that were invalid. I tried to maintain some connections, but I broke most of the crane arm animation in the process. There was no other way to fix it because of the expressions. If you want to, you can recreate those expressions.
The bind pose errors are probably not anything to worry about. If you really want to resolve them, skin the entire model instead of just the hook. But honestly, the easiest path for you if you want to use the old file and not the Quick and Dirty one is to just not use linked xform and use the skin only. If it was a cable or something that needed counter animation in the middle linked xform is great for that, but as a single A-B connection skin works just as well, though has other problems with the old setup.
Best Regards,
