Cordless Blinds - bad luck or something different?

Hey all.

Over the past year, I've had bad luck with standard, non-motorized cordless blinds. I've had to replace 4 due to the tension mechanism failing (from what I can tell).

• I've tried gently exercising the tension mechanism as suggested frequently online. This does not work.
• I've checked for knots and have found none (I typically expect these for corded blinds).

I've been purchasing the Home Depot brand. Do I need to go for a more expensive brand? Did I just get a bad lot? Should I go for corded for supposedly easier troubleshooting?

Thanks in advance!