Not familiar with Curados, but I had a similar problem with a different brand and had to send it back to the manufacturer. Had it looked at and worked on by 2 different reel guys to no avail, so I sent it back to the manufacturer. In that case it had to do with the centrifugal braking system, but I'm not sure if the Curados have that type of braking system or not.
Do the Curados have a magnetic brake that adjusts from the outside or do you have to adjust from the inside? Also, when you adjust the tension knob does it increase the drag and slow the spool down? If not then it could be the tension knob is not putting pressure/drag on the spool.