Mitch- not intended as an explanation, hence 'sort of'. Reducing and removing hum is a black art.

Barbara - pleased to have given you some ideas and that you've solved the worst of the problem. Removing anything will affect other aspects of the recording - your ear is probably the best guide to how successful it is.

If you can't remove it completely to your satisfaction you may be listening for the hum; get someone else to listen to it. It could be better than you think.

Stu