If the grind keeps changing, take a record before buying burrs. Note the coffee, setting, dose and output, plus the last cleaning and burr replacement. A useful comparison is the same grinder before and after its documented cleaning routine.
Check the cleaning result before deciding that a weight or calendar threshold means the burrs are finished.
Use the maker’s criteria
Mazzer’s Philos manual calls for grinding-blade replacement when ground-coffee quality or quantity declines, and assigns that work to skilled technical personnel. It does not supply a universal weight limit for every grinder.
For a commercial machine, identify its exact burr set and ask for that model’s maintenance criteria. A use record can support the decision; it cannot establish that every type of burr wears out at the same weight.
Separate buildup from wear
Mahlkönig’s E65S manual has distinct procedures for the bean container, outlet and grinding mechanism. It warns that damage to the outlet can let grounds adhere and cause dispensing fluctuations. That is a reason to check the complete permitted cleaning routine before attributing dose changes to burr wear.
Use only the products and access described for your machine. Do not use a generic monthly tablet schedule, add water to the grinding mechanism or reach into the burrs. A cleaning method allowed for one grinder is not approval for another.
After cleaning, keep the coffee and routine comparable and note what changed. If the problem remains, have the grinder inspected. A changed taste, clumping or noise alone does not prove which part needs replacement.
What replacement should include
Confirm the correct burrs for the grinder, the condition of the mounting surfaces and the manufacturer’s fitting and calibration procedure. Mazzer’s instructions link clean mating surfaces with correct alignment. A new part does not remove the need for correct assembly.
Don’t assume the old collar position will reproduce the old result. Ask the technician to explain the checks completed after fitting and how to resume the normal dial-in process.
If the grinder jams, smells burnt or has an electrical fault, stop using it and arrange service. Send the model and before/after record rather than opening the drive or motor to look for a cause.
Sources: Mazzer Philos instruction manual, IPH0L001S, section 8, PDF page 14; Mahlkönig E65S operating instructions, cleaning and outlet care, PDF pages 24–28. These support specific cleaning and service boundaries, not a shared burr-life rating.