Hello S.,
You likely have a B&S Exi725 on this trimmer? They only run at one speed.
Carburetor dip is "overkill" on these carburetors. It will not hurt them, but there is very little to ever go wrong with them except the center insert with the jets or the float needle gives out from Ethanol fuel exposure in the heat.
While you are cleaning this, make sure to empty the tank and clean the fuel screen molded into the bottom of it.