[mikethedruid]

With the set turned OFF, attack an ohm meter across the tuning cap. Turn it through its full rotation, and note if the meter shows any change of resistance. Do this for each section. It sounds to me like one of the plates may be shorting to an adjacent one. In that case, some very slow and careful persuasion will be needed to bend it back to where it no longer shorts. There WILL be a resistance because the cap sections are connected across coils. If you want the clearest readings, unsolder the wire from the stator section before you measure it, but that is not really necessary. A short will show up either way. Often, careful observation is all that is needed to find it, not even an electrical check.