Afaik based on brief observation, a head is a ceramic rectangle with an embedded wire. I almost called it a filament but that's pronably isn't accurate in any way. What it is basically is a magnetic pickup coil. Can it be severed. I'd have to say absolutely. Which would probably necessitate a total replacement of a similar assembly.

Of course I'm alluding to info garnered at least 20 years ago. So regard every last bit of the above as total bs.

It seems the nearest obvious equivalent in a roundabout sort of way is a metal detector. It fumctions or it's function is very different from a disk drive's magnetic pickup. But may help to illustrate what's going om kinda sorta. A coil of wire is attached to a circuit that's able to make sense of what is being presented to the coil at the business end.

The coil could be broken or the amp chip for the head is dead. Those are the two common issues in my experience when one head has no signal.

This drive is old enough to still use diode switching for the heads - D11-D18 in the schematic at https://electrickery.hosting.philpem.me.uk/co … hHHHDFloppy.pdf
If one of the diodes went bad (open or short) you'll loose signal from that head. I'd start with that before messing about with the heads themselves. In theory the head coils could be rewound, in reality I've yet to see anyone succeed doing that.