You can do it as follows:
 
1.  Create a CSV file containing part number and the fields you want to update.  Once it is ready to go, you need to get everybody out of DBA while you do the next steps.
2.  Copy the following 3 files for the company you are in:
BKICLOC to BKICELOC
BKICMSTR to BKICEMTR
MTICMSTR to MTICEMTR
3.  Use Import Inventory and import the file from step 1, indicating R to replace existing part numbers.
4.  Run the Inventory Error Report in the Import menu to be sure there are no errors.
5.  Do step 2 in reverse to copy the files back

If there is somehow characters in the import tables that are corrupting your data somehow, you can go to UT-A and use DBAIF program on the 3 files with the "e" in the file name.  That re-initializes the files from the data dictionary.