If the recorder has a UHF output, check it's not on these channel numbers: 46, 42, 50, 45, 49, 43, 30 - or within 1 of them - so not 29-30-31, 41-42-43-44-45-46-47-48-49-50-51 - if it is then it will likely be generating interference... either disable the UHF output and go SCART (the modern solution) or move it somewhere well out of the way - channel 21 or 68.
The retune has involved a change in the way the digital channels are encoded (previously it was 16QAM, now it's 64QAM and 8 times more susceptible to interference as a result of that)