A:AnswerTHE "RECORD" BUTTON SHOULD WORK JUST FINE. THE HUMMING SOUND IS NOT NORMAL. YOUR PLAYER SHOULD BE ABLE TO RECORD WITH NO ADDED SOUNDS COMING FROM THE RECORDER. PERHAPS TRADE IT IN FOR A WORKING MODEL.
A:AnswerYes, You can record audio from an external audio source through the AUX IN JACK . Note : The MCR-100 is a mono player/recorder,
so only the left channel will be recorded through the AUX IN JACK.
A:AnswerYes. You can buy a mono adaptor to plug your headphones into and then plug it into the headphone input of your cassette recorder and you will get mono out of both sides of the heaphones.