Thank you TVSon,
Before I had a chance to try out your solution, I tried the following and it worked.
1. I temporarily locked series ABCD and made Manual active again.
2. Loaded up the Items successfully this time, although all Items were marked as Manual but with the correct codes starting from 60000.
3. After the DTW load, I went back and loacked manual and unlocked series ABCD again and made it default.
Thank you anyway for your reply, will try it next time.
Ajay Audich