I had to change from a three prong to a four prong

You need to remove the grounding strap between the GROUND (Green) and NEUTRAL (White) wire if it still attached. A four prong configuration has a ground independent of the neutral wire. If the ground wire is too short to reach the terminal block, I suggest you install a longer wire of the same gauge, find an alternate location that you ground the wire to the case, or pig tail the exisiting ground to accomodate. The following link explains the 4-prong configuration:

http://www.fixya.com/support/r793520-3_prong_4_prong_power_cord_conversion

Nearly all modern appliances require a 4 prong power cord now. If you have any questions about this repair, please let me know. I hope this helps you.