I read about the CONTOUR mission which used an internal solid rocket motor to change the trajectory. Have there been other spacecraft using a solid rocket motor which is not jettisoned after usage?
above: from Gunter's Space Page
According to Gunter's Space Page's Muses A Lunar Orbiter (Hagoromo):
It was launched piggy-back on the Muses A (Hiten) probe into a highly elliptical Earth orbit which passed by the Moon ten times during the mission. At 19:37 UT on 18 March 1990 as Hiten approached its first lunar flyby, the small Hagoromo spacecraft was released into lunar orbit, making Japan the third nation to orbit the Moon. Although the S-band transmitter aboard Hagoromo had failed on 21 February 1990, the ignition of the Hagoromo deceleration rocket was confirmed by ground observation at 20:04:03 UT, the estimated orbit was 7400 × 20000 km with a period of 2.01 days. No contact could be established after orbit insertion.
@DavidHammen's answer to the question "Was Hagoromo's capture into lunar orbit ballistic capture or more propulsive?":
A solid propellant (KM-L) retrorocket with a mass of 4 kg was mounted inside the spacecraft for orbit insertion.
@DavidHammen's answer to the question "How could tiny Hagoromo have been seen visually from earth confirming its lunar orbit?" is a click away and worth the read, so I won't re-quote it here.
See both (either) linked question for more images of this kawaii spacecraft and it's "parent" craft.