The main nozzle feeds fuel through the "H" circuit of the carb into the venturi. The back side is that 3/16" round brass thingy in the metering chamber. It does NOT come with the kit. If you change it be sure to REMOVE the "H" needle first or you may destroy it.
BTW, I hope that you are using an OEM Zama kit.
This could be main nozzle but you won't know until you fix the rest of the carb.
You should also clean the needle seat with a Q-tip stem dipped in carb cleaner and twirled around. Get out your magnifiers to inspect the seat when you are done.
Be sure to check and probably set the metering lever height. The old one might be usable and correct but should be checked. A new one MUST be set.
Once the carb is reassembled you should pressure test the fuel input to verify no leaks. It should hold 7-10 psi indefinitely.
BTW, what model saw is this on?
Thanks for the advice regarding the nozzle. I'll have a look and see what I can find this afternoon.
This is a new saw to me. In the interests of ensuring it's been put together in the first place, is the L screw the longer of the two?
The kit is still in the post. Not sure if genuine or not.
I'll follow your advice when cleaning.
The metering height was set quite high but making it level with the carb body (not sure if that's correct) didn't seem to make a difference.
I pressure tested it previously and it was fine but will do so after the rebuild.
The carb is on a 2001 Husky 365 Special. Not sure if it's original or not but I believe Aussie Specials continued to have Zamas and open port cylinders at least for a while after the US got the Walbro and closed port cylinders.
Thanks again, very helpful.
Tom.