Converting h:mm:ss to hh:mm:ss

Im doing a school project and i need to transform a column that contains both hh:mm:ss and h:mm:ss into only hh:mm:ss. I have tried string manipulation, string to date time but nothing changes. I would apreciate if anywone could share a way to detect if a record only had 7 digits and add a 0 to the start. While i could do it in the file itself that wouldn’t add any value to my project.

Thank you.

event-notification-rpt-lastmonth.txt