Markd51, Lloydc, Mofimadness,
Thanks for your replies and suggestions. It is indeed brush positioning issue. I carefully examined the brush assembly last night, and found that with a little bit brute force the brush holder can actually be rotated further more to make its tip pointing at the platter axis - hence covering most of the surface. The brush assembly was a bit stucked probably because of age.
However, I found that HW-17 is indeed not very effective, especially on noisy (no visible dirt though) records. Some of those don't even get noticeable improvement after multiple cleaning sessions and have to be cleaned manually using alcohol based solution. I also found that, at least in my collections, RCA "dynagroove" records tend to look mint but sounds noisy even after extensive cleaning. I read somewhere saying "dynagroove" is a special way to cut grooves in order to compensate groove distortion. Is it because of this dirts tends to get into grooves easier, or this special shaping makes it easier to damage the grooves?
Thanks for your replies and suggestions. It is indeed brush positioning issue. I carefully examined the brush assembly last night, and found that with a little bit brute force the brush holder can actually be rotated further more to make its tip pointing at the platter axis - hence covering most of the surface. The brush assembly was a bit stucked probably because of age.
However, I found that HW-17 is indeed not very effective, especially on noisy (no visible dirt though) records. Some of those don't even get noticeable improvement after multiple cleaning sessions and have to be cleaned manually using alcohol based solution. I also found that, at least in my collections, RCA "dynagroove" records tend to look mint but sounds noisy even after extensive cleaning. I read somewhere saying "dynagroove" is a special way to cut grooves in order to compensate groove distortion. Is it because of this dirts tends to get into grooves easier, or this special shaping makes it easier to damage the grooves?