If you have FM Advanced, you can generate a Database Design Report, which tells you (among lots of other stuff) where every field is being used: a nice little list that you can process (manually…).
If you “only“ have FM Pro, try to delete the field; if it is referenced in a script, you will see a message to that effect. Replace the reference (i.e. use your Minutes field instead of the Hours – and don't forget that you will need to change the logic) and repeat until no message appears.
Admittedly, a bit cumbersome, but better than doing it “by hand“ …
Thanks - I was just looking into that - wow - a lot of data to weed thru - but - as you say - its still better than opening each individually (yes I have advanced)