Chainsaw Repair

A mate put me into this repair for an old boy if i get it running for him theres an old mac in his shed for my collection
Has a walbro wt carb well thats what I can find starts ok dies on acceleration so I thought ok mix screws HMMMMMM I cant find any   so tightened loose carb screws and put carb back on now starts and runs but needs 1/2 choke to get the revs up
So off with the carb again and where I presume mix screws should be is one hole and next to it a plastic plug I can't see if there is a screw in it and I have not tried to move the plastic plug.   Should there be a plug where the hole is.     With the choke on 1/2 again I can get plenty of revs so all I can think is its starving for gas
Anyone have any ideas  I have never seen a carb like this cheers pete

I think most of the yardmaster stuff over here is MTD yep whipper snipper trimmer strimmer all the same,  going to try find some numbers on that carb today, just cant understand why  I cant find a way to adjust the mix, will try and prise out the plastic plug that is in the hole    The two holes are where i would expect to find mix screws, but as I said 1 has a plastic plug one has nothing, maybe one has fallen out I have no idea if it wasn't for the carrot of a saw at the end of it I would send it back but it's also an old boy's machine so you gotta help when you can cheers

OK it.s an mtd lt31 anyhow pulled and stripped the carb reassembled it ntried to remove what I thought was a plastic plug I couldn't move it so down to the 2 dollar shop for some stronger reading glasses.
Well what I thought was plastic is actually a metal piece round with 1 small flat on it and on the side of the carb is an L indicating to me its the low jet and with the way this thing behaves which is dies on acceleration it makes sense'
Are these jets adjustable if so how I have never seen one before
I can get it to run with high revs but need to use 3/4 choke
 all help gratefully received
Just took a torch and my new glasses outside to check the name I was wrong it says Yard Machines  not yard master Thanks 660 for making me check up on myself

Tried  to download a workshop manual for it No luck user manuals only   , Now I have a new tool bar and unwanted prize offerings popping up, and don't have the computer smarts to fix it
Whenever I googled carb adjustment for mtd LT 31 I ended back on the same site and the answer was carb adjustment take it to your dealer.   Well if a dealer could fix it the old boy wouldn,t have it back with a repair sticker still stapled to the handle
Has any one an idea I looked at the carb again and it may take a special tool to adjust the L jet  The top is round with a flat face  Looks like I could file out a small socket and leave one face on it

I can get plenty of revs but needs to run with 3/4 choke so to me its not getting enough gas

I don't think this thing is more than a few years old, diaphragm looks and feels good wondered about adjusting the metering lever to let in a bit more gas