Are you certain that your TiVo doesn't still have a MAK? The modification doesn't delete it but perhaps you have also replaced the HDD.
I posted a How-To transfer via a browser using the MAK (and how to find it) in this thread but I've not read anywhere that it can be done without one. I believe that the MAK is an encryption key for the recordings.
In that thread Darren posted a caution about backing-up to retain the MAK.
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