Oh! - I didn’t get your explanation until I went in to fix it… sorry, I see now what you were saying was that the prism() call I was using was the one I wrote, not the BOSL2 one, and that it was faulty. (I initially thought you were saying that it was the BOSL2 implementation of prism that was faulty.) So I’ll take that out and use the wedge call from BOSL2 instead (at least until I can understand why my prism() call didn’t work as expected.)
That also explains why it initially had worked and then stopped working in a later revision - it was because I had started removing the dependency on BOSL2 and was replacing some of their modules with my own local versions. I guess I initially missed the breakage because when I tested that update I hadn’t needed to remove any of the parts from the plate before printing. (Usually I just print the parts that have changed but that time I must have reprinted the entire model, and it was only when the items were split that the problem surfaced.) Lessons learned.
Thanks for finding it! Much appreciated. I’ve now released the project here at Pitrex (Vectrex) cartridge by gtoal MakerWorld: Download Free 3D Models
Graham