You've almost certainly got a rubber belt wearing out. I've fixed a similar issue on a demon before. If you need help repairing, consider reposting on diyaudio. In my experience it's a super helpful group and people will help you identify the problem, find the proper replacement part, and install it. Really an amazing community, at least on the passlabs sub forum where I spend my time.
https://www.diyaudio.com/forums/digital-source/
https://www.diyaudio.com/forums/digital-source/