The Mellotron Group

Hi fellow Mellotron owners (especially the experienced one's or those who already had to fix some problems on the instrument...),

since a while one note on my M400 has rapidly become flatter and playing an octave has become close to a major seven interval. And it is, you may guess, the stiff pinch roller. I have found a description how to drench the roller into pure alcohol (must it be 100%? I have bought today a mix of 70% / 30% water...), but that was not so easy to do. Do I have to get the pinch roller off from it metal axis to get it seperate into the bath of alcohol or is this no good idea (cause it will demage it...)? Has someone made a detailed description how to clean the pinch rollers, including photos for such folks like me who are more musicans than diy guys :-) ?

Any help & advice would be great!
Greetins, Thomas