Dust in the sliders, button and circuits can provoke a typical JD-800 berzerk (auto-programming...).
This effect is like a ghost acting in the synth. If you don´t use to change program while playing, turn off the banks edit mode. (just press bank A-b-C-D to light off and then save the patch.
You will also note, when some parameter is changed because dust, a "point" will light in the painel, like if you have done it.