Bowl and orientation tooling
Observe how incorrect presentations are rejected or recirculated and whether repeated circulation marks a visible top. Test the bowl at normal working fill levels rather than only with a carefully arranged small quantity.
Rail and escapement
Check the full tolerance range through bends, restrictions and the final release. The rail should control the closure without squeezing a variable top or allowing the shank to overlap the next part.
Controls and buffer
Confirm low-level response, cap-in-track sensing, no-bottle/no-closure logic and what happens after an emergency or line stop. The feeder should recover predictably without releasing doubles or starving the press.