My husband has Magix Lab Cleaning 2013 but when he goes to use it, a screen appears saying levels too high or levels too low. Is there a way we can get the levels back to normal and he can carry on using it?
With a right click on the recording button you can open the recording settings panel in Audio Cleaning Lab and you need to select the audio input there.
Depending on how you connected the tape deck to the computer, you need to select the input accordingly.
For example, if you just plug a cable from the headphone output of the tape deck into the microphone input of the computer, you likely need to select the internal soundchip of the computer as the input device. The soundchip is usually made by Realtek. The device is likely called something like Microphone (Realtek).
Make sure the impedance of both the output of your tape deck and the microphone input on the computer are about the same, or otherwise the sound might be way too quiet or way too loud and distorted. Don't connect a line output into a microphone input.
If you are using a laptop with an inbuilt webcam it might also be available as an input device in the audio input settings and it might be already selected resulting in the erratic "Level too low", "Level too high" messages, but that is just guess from my side. You need to switch that to the microphone input.