I meant to suggest that maybe you had a leak... but sometimes residual vapors from solvents and such... take a long time to depart.
I have taken one Welch pump apart and concur with your advice not to.. unless there is evidnce of internal damage.
I once rebuilt one single atage pump, even going so far as to make a new main shaft. It was necessary to resurface the rotor and vanes. And then "reseated" ( a euphemism creating a light interference fit!!) them into the pump ring. If the pump has had a hard life, the circumferential seal area ( about 42 deg arc between intake and exhaust ports) can get scored and will require something like tha above treatment to restore it to health.
I am continually impressed with the simple genius of these pump mechanisms.
Dave Cooper
Created on Wednesday, April 25, 2001 3:13 AM EDT by David Cooper