The 737 MAX jet again was the source. Boeing delivered just four of them last month as it worked to fix an electrical grounding problem.
The problem affects a backup power-control unit and two cockpit components. Hundreds of planes made since early 2019 could be at risk, Bloomberg reports.
The 737 MAX crashed in 2018 and again in 2019, killing a total of 346 people. Boeing has had problems with other planes, too.
At the same time, net jet orders were positive in April for the third straight month. Boeing received 25 new orders, including five for 777s and 20 for 737s, compared with 17 cancellations.
And Boeing delivered nine 787 Dreamliners in April, the highest monthly total for the plane in more than a year.
Boeing recently traded at $227.86, down 2.2%. That was stronger than the recent 0.85% drop for the S&P 500 index.
Boeing has gained 20% over the past six months amid optimism over economic recovery.
TheStreet.com Founder Jim Cramer discussed Boeing earlier this month, following a Bernstein note that upgraded the company to hold from sell but was negative overall.
In April, Cramer said a turnaround is possible for Boeing this year.
Boeing posted its sixth consecutive quarterly loss for the first quarter. It cautioned that the COVID pandemic continues to challenge the global aircraft market and unveiled the pause in 737 MAX deliveries linked to the electrical fault.