Hi Matteo–
I’m wondering if you have tried using an anticondens fluid (Duponol is a brand that I am familiar with) on your Yamaha 300 series recorder. I think it won’t prevent condensation, but it does make it easier for the water to travel through the windway instead of building up in there.
In addition to sucking and blowing, another trick that I’ve found which works for me is to fold up a small piece of paper a few times (to about the size of linguine or fettucini) and insert it into the windway through the beak to soak up moisture when it collects. I just make sure that the paper doesn’t come all the way through the windway and touch the edge of the ramp. It works in much the same way as an oboist’s feather.
Since you can oil a wood recorder, and since many recorders now are made of wax-impregnated wood, it is my understanding that the only wood in a well-maintained recorder that will actually absorb moisture is the block–something that it is supposed to do. So don’t worry.
–Dick–