This demonstration guide answers one field question about a groove that lets the drive links rattle. Measurements come before parts, and the notes are not a generic equipment FAQ.
Diagnose before replacing parts
Start with groove width versus a new-chain drive-link gauge. That reading separates a groove that lets the drive links rattle from adjacent faults that share the same complaint.
If the measurement is out of spec, treat the bar as the primary path. If it is in spec, do not replace the bar just to complete a parts list.
Repair the failed system
The usual correction is the bar, installed to the documented spec for this complaint.
A demonstration shop records the finding so the next technician is not repeating a guess about a groove that lets the drive links rattle.
Stop before you make it worse
Do not pinching a worn groove closed with a vise. That shortcut hides the original measurement and creates a second failure.
If the machine still fails after the bar is corrected, convert the visit to a broader diagnosis rather than stacking parts.
Written and published by Ridgeline Small Engine.