Sewer smell coming from area in basemwnt where ejector pump located, had plumbing company send a tech out to check problem but he didn't open up cover to recheck pump since pump had been installed less then six months ,pump is almost a yr old now and still have sewer smell, I will call a different plumber if needed, this is my 2nd pump from this company 1st pump lasted only 3yrs. It ran constantly but I didn't have the sewer smell with the 1st pump, please advise..

Smell usually indicates a bad seal in the lid. Are you sure there is a dedicated vent, there should be 2 pipes, about 2" diameter coming out of the lid. One goes into the main drain, the other should go up through the roof as a vent.