Hey all, So I have this cassette recorder that works perfectly fine in all aspects (playback, fast forward, rewind, etc), but for some reason won't record audio onto cassettes. I try and record by plugging an AUX cord from my phone into the recorder's Mic jack (which makes the sound come out of the speakers), and I press record and play at the same time, which it then proceeds to play, but then when I rewind to listen to it, nothing's there. I made sure I went through the steps carefully, so I think the problem may be internal. The recorder in question is a Sharp Cassette Recorder RD-767AV, which I'm pretty sure is what they would use in schools (my old school is where I picked it up). Any advice? Thanks in advance.

P.S. I couldn't find another cassette-related subreddit about this kind of thing so I decided to post it here, hopefully I'm not being a nuisance