Here is another hanging pyx, in Dennington (Suffolk), courtesy of Fr Allan Barton in a Facebook article. The church is beautiful.
I find it quite similar to mine (see Hanging Pyx Revisited), but with a more complex hoisting system involving compound pulleys. It appears one would pull down on the tassel, and the pulley gear would be counter-weighted.I would imagine you have to use some kind of stick to push it back up.
For mine, you have to go to the credence to take the rope off the cleat (yes, like on a boat) and lower the pyx to the limit of the rope (loop at the end hooked to the cleat on the wall). When not needed, the pyx is hauled up from the same place.