Clone firmware from one device to another

We have some hardware devices that require a simple clone from one device to another. The reason for this is because returning our devices back to the manufacturer for a re-flash just takes too long. We would like to reflash the devices ourselves. What we would like is a nanddump of a good device with images that we can re-flash to 'broken' devices. The CPU in use is an Ingenics 4750. We have tried ourselves but we are unable to fathom out the correct parameters for NandDump with oob to be able to re-flash into a known good device but with corrupt firmware. What we are looking for is a simple way of taking a known good device, cloning the firmware to files and then using those files to update broken devices that have been returned to us from customers. If you know you can help, please post a quotation for the work. This should be simple work for anyone who is experienced in flashing firmware. Remote access to both a good device can be provided, and to a PC utilising usb_boot tools for writing to a 'broken' device to clone to can be provided. Skype comms essential as you will need to request booting of devices in real time during your work.