This doesn't really address your question, but given the effort and potential damage you might do to your R-09 in taking it apart without any experience, is it worth doing this as opposed to simply buying some HQ external mics and a small battery box? Otherwise, I don't have any knowledge or experience to be able to add to what others have posted.
Yes, external mic is a better option for sure, and I already have one, but I wanted to turn my R-09 into something "stand-alone", capturing music at good resolution in situations where I cannot use a separate mic.
It is now more or less clear to me that the risk of screwing the things up is too high for a noob like me, and it's not really worth trying to do it myself. I should really consider Chris Church mod when I'll have enough money for that.
P.S. Btw taking R-09 apart is a really easy task after reading invaluable guysonic's instructions posted on this forum. I did it in order to prevent problems with jack input, and now I would recommend anyone who can solder to do it before it breaks - sooner or later.