Yes, the M7 meter is pretty much of a spot and is famously off-center, as well as varying from body to body. I have two, and their spots are in slightly different places.
Using a small bright light I figured out, for each body, where the center of sensitivity is. Then I drew a rough viewfinder picture on an index card and marked the metering spot. Each card has the matching body's serial number, and the cards travel in the bag with the camera(s). I refer to the card occasionally to remind myself of that particular body's characteristics. I also write filter factors on the same card.
My method works well enough that I don't usually use a handheld spot meter with the MF gear. Every exposure from my Iceland trip, both chromes and B&W, was properly exposed. I had my PocketSpot with me, but never used it.