My MZ-N707 is having a strange problem where within 20 minutes remaining in SP mode (I usually record in LP4 via analog line in) it records to the MD but seems to have a problem focusing the write block and ends up with the tracks being almost correct but with segments of some other tracks being written instead. If only one track is written it usually affects earlier tracks in the same way and recording anything afterwards has the same problem. I've checked it out thoroughly with different discs and recording modes but the problem is the same but doesn't occur on the first 50 mins of recordings which is confusing.