Not sure if this same issue affects the Minolta Flashmeter V, but it certainly does affect the Minolta Autometer IVf, its contemporary in the meter evolutionary chain:
On the Autometer IVf, there is a metal pin which is revealed when the hemisphere is removed. The pin is normally depressed by a raised surface on the underside of the black plastic ring around the white hemisphere. This same pin is NOT depressed by the reflected light attachment (hole in the center) black ring. The pin is actually a switch and it alters meter sensitivity and readings.
It sometimes occurs that the pin/switch stops functioning, so that the white hemisphere presses on the pin but the switch does not alter the readings. Sometimes, if the pin/switch stops functioning correctly, if you merely press and release the pin multiple times it starts working again (oxidation on the contacts of the switch?!?!). In other cases, it was necessary to send it to Minolta repair to have the switch replaced. My own Autometer IVf meter acted up a couple of times, and pressing and releasing the pin multiple times would fix it. I once was on a photo workshop with someone whose Autometer IVf would not resume proper switch behavior, and he had to send it in for repair.
This switch mechanism was changed in the Minolta Autometer Vf, so that a metal pin switch is not used in the Vf, but a new switch mechanism was substituted.