I had previously had a problem with the jets not moving smoothly in the guide sleeves.  I had cleaned them and removed any rough edges, but eventually they started to stick again.  It turned out that one of them was badly worn which was causing the problem, but the other was OK.  I purchased a new jet and sleeve and installed them while the carbs were still fastened to the engine.

The old jet removed from the sleeve

The old and new sleeve together

The new sleeve fastened in place

The mixture setting nut screwed on

The old and new jet.  The new jet has a very smooth PTFE or nylon sleeve.

The new jet in place and connected to the fuel supply