You would think that tons of downward pressure on each section joint would result in a good electrical connection.  Well, corrosion increases the electrical resistance of the connection.  With bad connections, the antenna impedance can change resulting in antenna current readings that are not consistent with FCC licensed values.  Corrosion can also cause RF harmonics of the operating frequency to be higher than the FCC allowed limit.  Any harmonics IE: 2, 3, and 4 times the operating frequency, must be attenuated by more than 73 dB when the station is running 1000 Watts of power or 80 dB when running 5000 Watts or more of power.