There is apparently an adjustment screw, but it is hidden and you need to pull the plug hiding it out to get to it. The local mower repair thieves want $70-$90 to install a “carb rebuild “ in it, which consists of a few gaskets and maybe new fuel lines and fuel filter, for sure $90 if they change those.
The good news is, a new carb, two pump bulbs, two fuel filters, an air filter, spark plug and new fuel lines can be had for a very easy to swallow price of $10.50 to 22.50, most being $13.50 on ebay. It is quite easy to put the new carb on. I understand they need to make money but $70-$90 for a few dollars (literally) of gaskets and lines on your old carb is over the top.