There may be part # on the parts. A small engine type might have an
assortment on hand. Varnish can build up in the hole for the needle,
causing it to stick. Clean with a cotton swab and camp stove gas. Dry
with air. A proper carb man would clean out every orifice with high
pressure air.

I have a badly worn carb that would not behave until I wired snug
external O rings above and below the butterfly throttle shaft with
brass snare wire. It was so loose it wiggled and upset the mixture any
where near idle, or, it seems, whenever it chose to.

Terry K