Hoover Knob Height Adjustme...
$6.99
Product details
Part 38421128 is the height adjustment knob for the Hoover U6425 WindTunnel, also listed under model U6439900 and U64019RM. Turning it moves the nozzle up or down so it rides at the right depth for carpet versus bare floor.
When this knob breaks or strips, the height adjuster stops holding a setting, so the nozzle either skims over carpet without picking anything up or drags and bogs down on hard floors. The knob itself is a small, inexpensive part, but losing it turns a five-second adjustment into a machine that will not clean either surface properly. A new knob restores a setting that clicks into place and stays there through a full room of cleaning.
- Fits: Hoover U6425 WindTunnel, U6439900, U64019RM
- Part: 38421128, nozzle height adjustment knob
- Symptom it fixes: a height setting that will not hold or click into place
- Benefit: accurate, repeatable height for each floor type
It replaces the original knob directly, with nothing on the machine to modify. Confirm your model number matches the list above before ordering, since height knobs are keyed to the adjuster they drive and one from another upright will not hold a setting even if it looks the same. If the new knob turns but the height still will not stay put, the adjuster underneath is the next thing to look at.

