I've tried running the tiller into a rocky area I have, with the hope that it would clean off the tines. It was somewhat effective but not a great solution. What I end up doing is to take the tiller off and pick it up using the FEL and a tow strap so the tiller dangles over my wheelbarrow, and then use a large screw driver or knife depending on what is clogging up the tiller and just spend some time cleaning it off. It is much more pleasent for an old geezer to be able to stand up comfortably and work on this then to crawl around under the tiller trying to see what you're doing in the dark with bifocals...YMMV
I dump the mess out of the wheelbarrow into my FEL and take it somewhere to get rid of it.