On 10/30/21 7:38 PM, Jonathan Chapman via cctalk wrote:
  The belts are more or less all failing at this point,
even on the newer multi-gigabyte QICs. I finally had to stop extracting the good ones from
newer tapes, boiling, and reusing because that was not reliable anymore. Seems everyone is
using these nowadays:
 
https://www.amazon.com/gp/product/B08536J6Y5
 Thanks,
 Jonathan 
I've had great success using these on DC600-sized cartridges, including
Magnus tapges:
https://www.amazon.com/gp/product/B08536J6Y5
They're clear seamless polyurethane.
--Chuck