How can I force an overwrite of RTM from Astrid?

Somehow, RTM has lost hundreds of tasks that I've entered into it. Luckily, they are all in Astrid.

However, whenever I synchronize from Astrid to RTM, Astrid downloads tasks (none found) and then (I'm guessing) uploads changed tasks, but no tasks have changed. As a result, RTM has hardly any tasks, and there's no change to my local Astrid database.

Is there a way I can somehow push my Astrid tasks over the top of my RTM tasks?