Reconciling account - Starting Imbalance

[David Brock]

Okay, last night, I went to reconcile my chequeing account against my
statement, and although all the transactions were there, the "Opening
Balance" on the account was off by $450 (high, IIRC), so I couldn't
finish it.

This used to happen when I used Quicken, and the only solution was to
'un-clear' dozens of transactions, and go back to a statement where it
does balance, sometimes months prior, then work forward, statement by
statement.  Normally, there was a transaction that had been reconciled
and subsequently changed or deleted (careless clean-up, I won't pretend
it wasn't me)  I suspect that this is the cause again.

Is there some way of using the transaction logs to spot the trouble,
instead of repeating the un-reconcile, reconcile procedure, if it is
even possible?

Can anyone suggest how to troubleshoot and correct?

;-D