Here's a demo of the ACR25:
https://www.youtube.com/watch?v=m_YXCNpTfAg
As you can see the carousel is vertical and completely enclosed (except for the access door).
Pay attention to the transport as it loads a tape. Its very fast (vacuum threading). The capstan pops out from the back. It holds the tape also via vacuum. (Neither ACRs or TCRs used a "pinch roller" on the capstan.) The capstan is also aided by the reel servos on the take up and supply sides.
There's a brief view of the electronics unit next to the transport unit.