The bearings play a big part with the RX.
I have adjusted the pump on mine years ago. Ran much better, seriously helped the mid range madness that accompanied many a RX.
Mine was so rich is was spitting globs of fuel out of the card whist running in the mid range!
I read about the cure in Don Lowes RCM column a decade or so ago.
He'd received an article from Australia and published it in his column.
Worked great.