This demonstration guide answers one field question about passages that solvent never reaches. Measurements come before parts, and the notes are not a generic equipment FAQ.
Diagnose before replacing parts
Start with before-and-after passage inspection. That reading separates passages that solvent never reaches from adjacent faults that share the same complaint.
If the measurement is out of spec, treat the welch-accessed passages as the primary path. If it is in spec, do not replace the welch-accessed passages just to complete a parts list.
Repair the failed system
The usual correction is the welch-accessed passages, installed to the documented spec for this complaint.
A demonstration shop records the finding so the next technician is not repeating a guess about passages that solvent never reaches.
Stop before you make it worse
Do not soaking a carburetor overnight in a household solvent. That shortcut hides the original measurement and creates a second failure.
If the machine still fails after the welch-accessed passages is corrected, convert the visit to a broader diagnosis rather than stacking parts.
Written and published by Ridgeline Small Engine.