I have a plastic head chugger and a SS head chugger.
Both had a "plastic" or "solvent" smell, the plastic head being worse.
On tearing them down, the impeller appears to be the main culprit.
Here is how I got rid of the smell:
- Remove the pump head, take it apart (only takes a couple of minutes).
- Scrub all the head parts with warm water and dish detergent.
- Dry, then wipe down with a q-tip dipped in alcohol.
- Scrub with dish detergent again
- Soak overnight in hot oxyclean solution
- Rinse, dry and reassemble
It only takes about 15 minutes, total. Give the plastic part of the impeller special attention.
These are very fine pumps, they simply have a little manufacturing residue that needs to be cleaned out.