I was able to follow along and created a dummy wallet but when I hit broadcast I received an error "error: The transaction was rejected by network rules. (258: txn-mempool-conflict)"
Does the pay to field in electrum need to be set to the same exact address as the original transaction that had too small a fee? I did change the address in my example so perhaps that caused the issue?
did you get this resolved? I was having the same problem