have a 3PJ myself. suggest, u try swopping crystals .. u'll be surprised at how sensitive they can be. when they work well, they give no probs. but if they are cracked, etc .. it's hell trying to trouble-shoot.
not sure if u need to get original futaba crystals? but FM/PCM use the same crystals, as far as i am aware of.
also, go scrutinise the antenna wire CAREFULLY.