Hi,in your posts, it seems you are just connecting stuff and seeing if it works, if it doesn't you don't provide any necessary info like what the applied voltage was, what current it was drawing.
Do you have a DMM to measure your circuit conditions?
One that will measure up to 10A are quite common and at good prices.
DMM will be indispensable in you implementation of this project and help us immensely.
Tom...... 
Question, Did you look and analyse how the original chopper, you got the motors from, accomplished its goal?