New battery, freshly charged - 12.56 volts. Starter bendix engages flywheel but won't turn engine. Replaced solenoid, checked/cleaned all connections. Have 12.56 volts on battery side of solenoid, turn key to start position have and 12.56 on starter side of solenoid when starter is not connected, but when starter is connected the voltage drops to 3.4 volts. connected starter to batter via jumper cables and starter turned engine over as designed. Any ideas on what/where problem is?