How to identify extended ASCII characters and replace it with a space

I have a COBOL program that reads from an ISAM file. For few of the records in this file, a field (say FIELD123) has extended ASCII characters along with ASCII characters (example - 410090¶). When I try to write the record in the output sequential file with extended ASCII character, then the program fails. In order to confirm if this was the issue, I moved spaces to FIELD123 and then tried to write the record. This time the program did not fail. 

I need your help with below activities:

# How to identify extended ASCII characters?

# If there is extended ASCII character in a field, then replace only the extended ASCII character with space but retain the ASCII value from the field

Thank you!!