Perfect Vinyl Forever

I own and occasionally use an Ultrasonic cleaner.  Most of the time I clean with an old Nitty Gritty machine that I converted to totally manual operation.  I spin the record by hand to "scrub" in both directions and I then thoroughly vacuum away the cleaning fluid; again done with manual rotation.  For almost all my records, this kind of cleaning is sufficient.  But, on a small handful of used records I've purchased, even the most thorough cleaning did not get all of the crap out of the groove.  I thought the noise and distortion on some of these records was from groove damage.  But, following ultrasonic cleaning a small number of records improved dramatically, evidently from removing gunk that was practically glued to the record.  It is such a small number of records that cleaned up better with ultrasonic cleaning that I do not think it is an essential tool; but, it is something that does work.