Hi, everyone! I've got a problem with recording on my 688. I put a cassette with prerecorded stuff, then select channels. When I pres rec - diodes become solid so it show that the record is on, signal comes to all of tracks. But in fact when I try to listen to what I recorded - there remains prereocrded stuff. So, it doesn't even erase the tape. Can anyone help me with that thing? No visual damage on chips on boards. Where and what should i check? Many thanks!