we've had lots of problems trying to change AS/400 tables after the initial event. Here's what we had to do to solve the problem (you may be able to miss out a few of these - I lost track of all the various combinations....)
1 save away the data from the AS/400 table (I just used CPYF)
2 change the column in your table in test
3 delete table from database then regenerate
4 copy data back in (used AS/400 one-off program to "map" the changed field)
5 needed to go into any applications or UBEs using this table and ensure all code is still correct - in particular we had to re-do anything that referred to the TABLE instead of the BUSINESS VIEW (insert into... etc)
6 had to delete the SQLPKG referring to the table - either OWEXPLORFJA or the specific UBE sqlpkg
7 run the application or UBE again to regenerate the SQL statements with the correct columns.
then advance project to production, repeat steps 1, 3, 4 and 6 using the production libraries instead of the test/dev libraries.
long way around, but it's the only way we could get our changes to work properly.
Sharon