The older LGB motor blocks only used 3 wires as one motor lead was tied to one track power pickup. I removed the motor, trimmed the lead that went to the track power and added a forth wire from the motor directly to the decoder as well as the 3 original wires. Also one should remember that LGB used 6 volts for the '5 volt' bulbs (all moguls). Some users liked the 5 volts better on old steam engines as this gave a dimmer light.