I have an Account there too but i do not trade with it,
From time to time ThinkOrSwim upgrade their Software with New Functionalities.
I do not know honesty,
if you can take that kind of Data that you want from there.
But i know that have friendly Online Support,
you can contact with them and to ask for your Issue.
For further Help to your Issue,
i know that exist 2 other Companies that you can buy that kind of Historical Data.
One is the: TickData: http://www.tickdata.com/
and the other is the:
CQG Data Factory: https://www.cqgdatafactory.com/
By the Way,
i do not know from where you can take that Data without to pay nothing.
A Solution to that Issue,
is to provide that Service your Broker/s to you.
In that Case you must contact except of ThinkOrSwim and with the other Broker/s that you possibly have.