Both of my installs, meaning the test as well as my regular Plus version are missing these assets. After performing an EDR, deleting the packages, and downloading assets again, the same two remained inactive. In the end, I replaced the mechanism with one I freshly downloaded from Jointed Rail, and the Bogey was replaced with a similar one from another locomotive. It's not silver, but at least the locomotive is not missing the bogies and my sessions are not missing dependencies. So much for Trainzing these past couple of days, and so much for testing.
I usually don't complain much and generally fix stuff and continue, but this is truly a ball buster, and I feel for those that are technically challenged and only want to play with their Trainz game. I'm lucky in this respect, but it makes me wonder how many people purchase the program and toss it due to errors such as this and never consult the forums for assistance.