the cam and the wheel (or guide as you called it) can wear,leaving a groove in the wheel. this will cause the cam to bind on first movement. if it's the cam you have to take the shaft out of the carb. if it's the wheel (or pump control lever in the IDA schematics) then you can remove this very easily to replace it. Berg and Jaycee stocks both of these. The position of the cam can cause the pumps to squirt at idle,Bergs have made an adjustable version to combat this,but again you have to take the shaft,butterflies out etc. the spanish IDAs seem to suffer from the wear and the cam position problems as i have this problem too and have seen other IDAs with them