Jose Luis,
You may want to ask your repair tech to put in the spring for that one key that is for the lesser Yamaha flutes (400 series on down). They are the stainless steel ones as opposed to the white gold that is now on yours. This may cut down on your problem some.

Thanks.

I have been practising for some 20 hours after the repair and it looks I am adapting to the new trill lowered position. Still, for critical situations such as the coming student concert I may not take risks and will probably block the trill altogether, only for that specific event.

Unfortunately I have no time to send it back and have the spring modified or replaced, it normally takes some 10 days for the whole trip. But it is a good idea, provided the normal steal spring is stronger than the white gold one. Or that it could be tensioned to be stronger.

Jose Luis,

Just tension the spring more, You don't need special pliers either...This is a lot of consternation for no reason. Just bend it more. You may have to take the keywork off to bend it enough. That's the only difference.

It takes techs about 30 seconds to adjust springs on a whole flute, Unless they are not accessible like some G# keys. It only takes longer if we need to take things apart to access bending a spring more.

Playing with or without plugs is irrelevant as far as pitch and tone are concerned. Your embouchure placement affects things a whole lot more than using or not using plugs. Don't believe any of that nonsense.

Joe B

OK JB, I agree. The reason it takes so long to have it sent to Herman and back is that he is taking orders on previous appointment only and he is located far from my city.
I will do it myself. Anyway I have to change the B thumb cushion felt so I have to deal with keys anyway.