Not hard at all - but screws can be frozen/rusted stuck. Remove the screw top (bottle cap), withdraw slide with needle attached. Look into top of slide (top cover is in the way somewhat - lift that up) and you'll see fixing screws (2)- unscrew and mounting plate and needle asssembly comes free. Clip is just a circlip that you can pull out and reinsert into desired slot. If the screws are rusted and STUCK,.... soak em in penetrant for a good while. This didn't work for me and I drilled off the heads to get at the insides. Then drilled out the remaining screw and surround with slightly oversize drill (soft metal to drill) and used a tap/die set to form a new thread and bought a couple of oversize screws to refit the adpater plate and needle. Excluding the stuck screws - the process is simple - VERY. Of my 4 carbs - 3 dismantled OK - only 1 was a bastard to me.
Pic shows detail...sorry it's blurred - but you can see the fixing plate. You can remove the top cover to get better access by unscrewing the retaining nut. Be aware - this setting is critical for correct synchronisation/idling. I suggest you count the turns as you take it off and repeat that number putting it back on. That way you'll get a VERY rough setting. You can also roughly bench synch the carb rack once back togther by inserting a fine wire under the carb slides and adjusting these nuts till all wires free and catch at same point/time.
