Shares of Intuitive Surgical came under pressure Wednesday after a warning about a stalling problem that has affected a few of its robotic surgical systems.

THE SPARK: On Nov. 19, Intuitive said it had sent a letter warning users that the "instrument arm" on the system might experience excessive friction. The company said surgeons using the system may feel resistance, and if they continue to push that resistance, the device could stall and then "suddenly catch-up" to the correct position. That might cause an imprecise surgical cut.

Intuitive said one imprecise cut and two instances of perceived resistance have been reported out of about 55,000 total procedures performed with these types of instrument arms. It said no patient complications were reported.

While the company disclosed the problem on Nov. 19, it was posted to the website of the Food and Drug Administration on Tuesday.

Intuitive said it is performing inspections to test all affected instrument arms and making repairs or replacements as needed. The company said it has completed 70 percent of the inspections, and most of the devices had no problems.

THE BIG PICTURE: The da Vinci system uses robotic arms, cameras and a remote-control console to help doctors perform surgery with tiny incisions. It is used in gynecological procedures, heart surgeries, prostatectomies, urology procedures, and other operations. Intuitive Surgical Inc. makes money by selling the systems and disposable instruments that must be replaced after each procedure.

This year some experts have questioned the use of da Vinci systems in routine hysterectomy procedures, saying the procedures are more expensive but don't improve outcomes for patients. The Sunnyvale, Calif., company said in July that reduced hospital admissions and conservative management choices by insurers were hurting its business. Later the same month Intuitive received a warning letter from the FDA after an inspection.

SHARE ACTION: Intuitive Surgical shares fell as much as 2.8 percent Wednesday and closed down $2.13, or less than 1 percent, to $370.68. The stock is down 24 percent this year.