If you are noticing that tightening the spool tension knob dramatically increases resistance when reeling on your Curado I HG, your reel may be missing a part—Part #4895 ( brake ring gear)—to be exact
Opening the side plate revealed that one of my reels came from the factory missing this part.

The brass part is noticeably absent on the reel on the right. Both of these reels were bought new and owned only by me.


The reel has been sent back to Shimano and I'll update this thread with how the situation is handled.