How can this be?  You are content but you should change engineering jobs?  But, you are happy and thus thinking clearly and this could be the best time to maximize your next raise, promotion, and increase in job satisfaction in your engineering career.

It might seem counterintuitive to switch jobs when you’re satisfied with your current gig.

But too often job searches are a reaction to a sour work experience, and we end up fleeing from one bad job to another in our haste to get away. Instead, you should regularly update your résumé, watch out for plumb opportunities and carefully weigh how good you’ve got it with how good you could have it.  (US News: The 10 Best Times to Switch Jobs)
The Right Time to Look (Positive Emotions)

Sophrosyne is an ancient Greek concept of care and intelligence in conducting ones life: a tempered balance and wisdom.  The Romans called it Temperentia, Temperance the restraining of emotional excess.  When you are content you are thinking clearly and can best assess the true value of an engineering opportunity.

1.    Research shows that happy decision-makers are reluctant to gamble (1).
2.    Participants with “normal emotion processing” were engaged in a card-drawing task and they subsequently made safer and more lucrative choices. (2)
3.    Rational thinking and decision-making does not leave much room for emotions. In fact, emotions are often considered irrational occurrences that may distort reasoning. (3)
The Wrong Time to Look (Negative Emotions)

Most job searches are the result of an unfavorable work situation.  Something happened (new boss, loss of projects, corporate buy-out) that damaged that yellow brick road to upper management in your engineering career.  Now you are looking out of desperation and this leads to an emotional, rather than a rational, job change decision.

1.    You will not choose the best option. Angry decision-makers tend to make choices quickly and are unlikely to analyze their decision (4)
2.    You will Take Risks . In a study participants who experienced “frustrated anger” were more likely to choose a high risk, high reward– a choice the authors categorize as “self-defeating. (5)
3.    You will lower your expectations. In a study participants who had been induced to feel sad were likely to set a lower selling price for an item they were asked to sell; the researchers suggest that selling the item would bring about a change in the participants’ circumstances and thus perhaps a positive change in mood. (6)

The best time to look at new engineering opportunities is when you don’t need to.  The worst time to look is when you have to.