You couldn't get to the diaphragm with a screw driver unless it was a really really small one. There's a steel plate over it with only very small holes. Something could have fallen in there, that's the most likely thing if you took the white stock damping paper off leaving the driver naked and left them open to the air, or have something in the cups that could get inside like wool hairs or something. Or if you removed the dust cover from the front. I'm not sure that thin material that is left is fine enough to keep out particles.
If you have the driver exposed for any length of time, you should always put something over it to keep stuff from getting in. Some ortho drivers can be opened up and cleaned, but I don't think the T50rp driver can be, at least not easily.
This is something that people in the ortho thread have learned the hard way and warned about.
I did say it was a small screw driver. I did accidentally poke the diaphragm through the magnet holes once. No idea if that is what caused the buzzing. It's just a likely that something got into the drivers that shouldn't have been there.