Record where and when skipping occurs, then inspect glass cleanliness, rubber condition and installation.
A workshop should assess arm-angle, pressure or linkage issues.
For this question — How should skipping be investigated — keep the item, model and supporting references together.
Record the observed condition first, separating confirmed facts from points that still need validation.
For further review, provide overall and detail views with the relevant sample or drawing reference so the issue can be located precisely.
When documentation or mating conditions change, review the scope of the earlier decision instead of carrying it over automatically.
Final approval should identify the purchased model, valid revision and mutually accepted documentation.