We have a cheap "dalek" worm bin for food waste. When I scraped some
fertilizer out of the side hatch in the autumn, I had trouble digging
material out & there is basically a cavity about 20 cm high in the
bottom, with the rest stuck in place at the level of the top of the
hatch. I'd expected gravity to work it loose, but it hasn't. (The
bin is tapered so it widens downward, although it has a slight dent on
one side about halfway up.)

What's the best way to deal with this --- just bang on the contents
from the top with something heavy until it drops down?