Load64

Hello,
Recently got a 1530USB in an attempt to make some tapes from tape image files.
I've set up the 1530USB as per instructions, however I'm finding it difficult to make a cassette which will actually load.

In the first instance, I converted my tape to WAV and brought in to Audacity, which, when played, one can hear a pristine recording. However, once I send to the datasette, there are clicks in it (despite me moving everything as far as possible away from PC). Additionally, when I'm listening back to the 1530 (through the "listen" on the 1530 mic input), there is a specific volume setting which just creates noise  - around 73 or so - above or below is fine.

The behaviour is hard to explain, and I've recorded a video of what happens but it might be too big to add here.

Overall though, it's as if what is being output by the 1530 has lost all of the clarity that was inherent in the original WAV file.

Any help  at all would be appreciated, and I hope I have made some sense...

I attach a dropbox link to a video of the behaviour, and I hope that might make things a little clearer...

https://www.dropbox.com/scl/fi/6zt7sa6fogavoc9d7npc7/Untitled-video.mp4?rlkey=jg9934fyqc65w7keeedyuctaq&dl=0