This demonstration guide answers one field question about a swapped engine whose label no longer matches the deck. Measurements come before parts, and the notes are not a generic equipment FAQ.
Diagnose before replacing parts
Start with label spec versus installed parts. That reading separates a swapped engine whose label no longer matches the deck from adjacent faults that share the same complaint.
If the measurement is out of spec, treat the oil and plug as the primary path. If it is in spec, do not replace the oil and plug just to complete a parts list.
Repair the failed system
The usual correction is the oil and plug, 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 swapped engine whose label no longer matches the deck.
Stop before you make it worse
Do not using whatever plug is in the drawer. That shortcut hides the original measurement and creates a second failure.
If the machine still fails after the oil and plug is corrected, convert the visit to a broader diagnosis rather than stacking parts.
Written and published by Ridgeline Small Engine.