Carburettor specialist in parts for carbs old and less old. Excellent, helpful and they actually managed to produce a small valve for a pierburg carb from my 30year old camper. Everyone else I had tried told me no chance and not included in carb refurbish kits.
Have also had excellent service from The Carburettor Exchange in Leighton Buzzard By the way , the best place for a Pierburg carb is in the scrap bin . If you can find one the Weber conversions are so much better