It's unfortunate to hear about the issue with your cassette deck, but I can certainly help point you in the right direction for finding the replacement part you need. Based on the description you provided and the pictures you shared, it sounds like you may need to replace the spindle, take-up reel, or pinch roller, which are all critical components of the cassette mechanism. These parts are responsible for controlling the movement of the cassette tape, and any damage or wear to these parts can cause issues with playback or recording. To find the correct replacement part for your Denon DRR-M30 cassette deck, you may want to start by contacting the manufacturer directly or a certified repair center. They may be able to help you identify the specific part you need and provide guidance on how to replace it. Alternatively, you could try searching for replacement parts online through websites such as eBay, Amazon, or specialty audio parts retailers. Be sure to search for parts that are compatible with your specific model of cassette deck and that match the specifications and dimensions of the original parts. Before attempting to replace any parts yourself, make sure you have the proper tools and knowledge to do so safely and effectively. If you are unsure or uncomfortable with the process, it may be best to seek the assistance of a professional audio technician or repair specialist.