It is the only way you can test to see if it is sticking but this does not mean it won't stick when it is put back in. I had one that would work fine until you picked the mower up and tilted it towards you and this was enough to upset the level of fuel in the bowl and this was enough to make the needle stick. I haven't fitted a Briggs needle to this machine yet but I might do it tomorrow just to prove a point. It is a pain because unlike the earlier carbys with a tickler fitted you could actually see that fuel was flowing. With these primers it is a complete guess, and I would assume plenty of these mowers have gone to an early grave because of these dodgy float needles
