Are you columns in the destination of the correct data type, and are they long enough?
You may need to run the data transformation through a “Data Conversion” Data Flow Transformation so that you can map the AS/400 data type to a known SQL data type manually. When doing so don’t forget to set the column sizes wide enough for your text data.
I don’t think the problem is the size. I do use “Data Conversion” and increased the size from 50 to 500 for that particular column. I think the problem is SSIS cannot convert some data in that column using the default code page of 1252. It worked fine in DTS but it is not working correctly in SSIS?