We are looking at the right side of carb so L(left hand) looks to be correct. No 3 throttle slide is quite normal. My guess it has worn out in the body and throttle slide as they often do. Buy parts or carb from a reputable Amal dealer as some seems to sell strange combinations of parts that may affect performance. During the years the carb went through a number of modifications and they may or may not work together and may affect performance. The 626 (26mm) has a smaller body then a 928 (28mm). Amal carbs are simple but the modifications and differences makes it to a whole science to get them correctly set up.
My opinion is when they are correct they work amazingly well
Do not pump the tickler. Press it down until you see petrol coming out. My guess is you can omit the choke slide and start he bike from cold, only using the tickler. Should be tested before first occasion.
Remember, 4-strokes often leaning out mixture somehow when opening the throttle. Thus the need for accelerator pumps or CV-carbs.
2-strokes don´t do this
https://amalcarb.co.uk/
https://accessories.hitchcocksmotorcycles.com/Amal-Carburettors