Buying a new drive will be my last resort (thanks for the offer, though). The 800k drives are working now. It turns out that the heads were merely dirty, not bent.

However, there is definitely a tension spring which lurks below the head arm to keep it pulled down! It is hard to see, but when you shine a bright light, it can been seen attached down below. The next step is to obtain a small screwdriver so I can disassemble the head arm assembly further and see what to do about that spring.