mazzi has come to the rescue again! Thank you mazzi! I had completely forgotten about this point. If I remember correctly, I used to add the game folder to the System Path variable in System Properties, Advanced, System Variables, Edit window, which I am testing on Win7 & Win10 now. I'll report back in a bit, if this works as well. Using TDW's SH Validator is much easier though. Thanks again mazzi!
Update: OK, I was not able to get my radar to fail, as Bubblehead1980 reported, probably due to not having a new conn on my boat yet. However, I now have my old explosions back, and see all sorts of debris flying off of ships upon shell or torpedo impacts once again, whereas before, the explosions were rather plain most of the time... so that points to the library folder... Nothing definitive by adding the game folder to the Windows Path yet, but it seems to change things a bit. I'll do more checking on this sometime next week.