Use only the exact manufacturer's permitted cleaning method. A sharp tool can enlarge or damage an opening, altering how the arm is intended to work.
Understanding this situation
Some arms are owner removable and others require a particular release procedure. An apparent blockage does not authorise forceful dismantling or drilling, and spray geometry is not something to modify experimentally.
A useful next step
Clean only as directed with the machine safe and refit correctly. If the arm remains obstructed or damaged, seek the appropriate part or service advice. Do not run without it or enlarge jets to obtain more apparent flow.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.