I've never had this happen before. While removing one of my MMC2 cartridges from a Beogram 8002 (so I could test a newly acquired MMC2), the black base, with the connectors stayed behind in the arm. I was able to pull the base off the arm and it is fully intact. The new MMC2 works great so I am still in business while I decide how to get this one repaired. I looks like it would snap back on but I don't know what the orientation should be. I have contacted a couple of repair places for estimates so I'll see. The cartridge had been working great - the cantilever and tip are still good.
Here is a picture of the cartridge.