No disrespect, but I had lots of trouble keeping steady settings on my rappy 39, constantly tweeking curves and needle settings till one day i decided to take the idle needle out and grind the tip down so the mid range and top end were less affected by the position of the idle needle. Ahhh now it is what it ought to be. is it worth 500$ or more to avoid fixing a simple mechanical problem and end up with an unstable running that constantly needs to be tweeked?