I have one that is still working well in a SP world I started months ago.
Just the other day I started a new SP world as an experiment, using the seed word of ARSE.
I have spent a bit of time building the grinder, the same as the other world. The monsters are generating nicely, and they fall into the water chute, but when the hit the lava, nearly all of them don't drop the goodies.
![Frown :(](./images/smilies/frown.gif)
Help!