The black plastic splash guard doesn't retain anything, it just sits over the float area.
It's nearly impossible to just pull the top and do much for the carb. It really needs to be removed from the engine for a thorough cleaning, and parts upgraded for this new fuel.
More times than not, prying the top gasket out from under the metering rods, then back over them will bend the hanger arms, and throw the carb WAY out of calibration. It really needs to go on the bench, so it can be taken completely apart, cleaned, and re-assembled with new parts and correct settings......Cliff