Wiper Drive Noise

During final checks of the wiring harness prior to placing in storage while remainder of restoration work proceeds I found the wiper drive to be rather noisy. It's been freshened up with new wheelbox, cable/rack, and guide tubes. There is the expected and agreeable whirring sound from the motor but also a less pleasant clatter from the drive section. It does run smoothly, and there appears no distinction in how the original pieces mesh in comparison with the replacements. Is this something for concern or do these units normally make such noise?

Cheers