This demonstration guide answers one field question about a key that has moved a few degrees. Measurements come before parts, and the notes are not a generic equipment FAQ.
Diagnose before replacing parts
Start with timing-mark offset at TDC. That reading separates a key that has moved a few degrees from adjacent faults that share the same complaint.
If the measurement is out of spec, treat the flywheel key as the primary path. If it is in spec, do not replace the flywheel key just to complete a parts list.
Repair the failed system
The usual correction is the flywheel key, 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 key that has moved a few degrees.
Stop before you make it worse
Do not slotting the keyway to "advance it a little". That shortcut hides the original measurement and creates a second failure.
If the machine still fails after the flywheel key is corrected, convert the visit to a broader diagnosis rather than stacking parts.
Written and published by Ridgeline Small Engine.