My XL1 was fixed last year and the entire drum assembly was replaced by Canon.
A while ago, the drum started making noise. Whenever the drum spins up to record or play it whines. I took it in to be repaired and the guy just cleaned the drum. I complained that was still noisy and the guy insisted that it was normal for the tape mechanism to make noise. After a little arguing I decided to never go back there.
The whine is loud. The boom mic will pick it up. I have worked with XL1 for many years and it is louder than the normal tape mechanism. There are (currently) no other problems. Recording and playback are fine. No video problems.

Should I take it to another repair place? Do I need to send it to Canon?

Your best bet for a return to factory spec repair is no doubt Canon, and they are fast on the XL series.

If by boom mic you mean the standard XL1 mic, and you are speaking of mechanical coupling of vibration to the mic (not acoustic coupling though the air, be sure you he not overtightened the screw that holds the mic in place.

.