My experience with buttonholes here is your problem. You pull the art needle blood follows up the track, All art buttonholes should be in the up position, the reason is when you pull the needle blood comes out and leaves scab martial in the tunnel track. Well you say so does the art with it in up [position this is true put for some reason with the art needle in the down position I have notice over the last 13 years that there has always have problems with a needle point down, leaking around the site trouble cannualteding.So my recommendation is to stated a new buttonhole in the up position. Next google "Cushion cannualtion"and 'teardrop cannualtion" these two things should help with your problem. Additional info is that sometimes the buttonhole needles comes down along side of the tracked, if using "touch canualtion" you should fell the pulse of the vessel coming threw the tubing. and you know that you are on top of the vessel for cannualtion.I have notice that some buttonholes can't be cannualted with buttonhole needles this is due to the fact that patients in hard labor IE brick layers, farmers etc have a thicker vessel wall thickens that a buttonhole needle will not penetrated. It is OK to use a sharp only if you use "touch cannualtion" google it to find out more.
PS I hope this will help ,after you have change please come back and let us know how it work out[/SIZE]