Really depends which carb as to what can get clogged.
Here is some basics.
[1]Metering diaphragm hardens.
[2]Fuel pump diaphragm hardens.
[3]Then the metering passages clogs with old fuel and trash. These are usually behind the mixture screws.
[4]Filter screen clogs. Note: many of newer have a filter can clogged even it looks clean. Can not be clean, replace only.
Do not use tag wire or similar item to probe holes as some are check and are easily damaged.
Use only an Ultrasonic cleaner with soap and water to clean these. Carburetor cleaners can damage the internal check valves.
Also when replacing the needle and lever it must be set correctly; or, flooding or lean condition can occur. This one gets a lot of home mechanics.
On carburetors which depends on type even the nozzle can get clogged.
Some of these carburetor are so cheap now that even the repair kit is about same but others it well worth learning how to clean and rebuild. There is also carburetors that parts are not even available for now.
