I've had these sort of problems for a while now, with Dec jumping around all over the place. I have taken the dec motors off and adusted the worm gear so many times but it was having no effect. Constantly rebalancing the scopes also did nothing. Tonight though after reading this thread I uninstalled PHD then ran a registry cleaner, reinstalled the latest PHD and now it's guiding like a charm, best graph in yonks. Thanks peoples.
Keith