Thanks for your replies, here is one of the error messge from the SSIS Package:
Error: 2013-03-13 05:01:23.75
Source: Data Flow Task Flat File Source 1 
Description: The "output column "SELL_DSCR" (27517)" failed because truncation occurred, and the truncation row disposition on "output column "SELL_DSCR" (27517)" specifies failure on truncation. A truncation error occurred on the specified object of the specified component.
I've attached the properties page.
Can I simply change the code page to US-ASCII or add Unicode? The invalid characters appear to be extended ASCII values coming in from cut/paste functions in a distant system...
I'll read up on those attirubtes..