Minolta 100mm f/2.8 Macro D problem
I assume you are engaging / disengaging the AF/MF switch on the camera body correctly?
I had a Tokina lens that had problems with manual focusing which turned out to be the rubber grip being loose on the metal body. A little bit of carefully applied glue fixed it.
Yes, the switch is applied correctly.
How did you get glue underneath the rubber grip?