carburettor overflowing

[David.H]

David,

even when using new, I always lap the needle into the seat with a tiny amount of fine grinding paste.  

Once you are happy the collar is correctly placed, I would also give it a little lap.

Thanks...I have that technology! An ancient pot of fine one end, coarse the other grinding paste. I had not thought about the collar, of course that could be a bit sharp & sticky....but why was this nor the case when the original Zenith parts were new I hear myself ask ??
Back to the washers....how thick should it be & would changing that thickness have a similar effect to moving the collar?
D