Parking brake adjustment issues

[expeditionroasters]

After 60k on my 2019 Bullitt it was time to adjust the parking cable as it was not holding on sloped ground anymore.
Rear brakes were changed about 5k miles previously.
The big 'ol resonator on the Bullitt's are in the way so had to drop the exhaust some to get to the adjustment nut. Tightened it down more and the hand brake engaged nicely.
After about 1k miles it's back to being pulled all the way to engage and not holding on sloped ground again.
Before i drop the exhaust again and check are there any suggestions on why it may have loosened back up?

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[BigR4444]

Ive been planning on getting my car up in the air and doing this myself as well (when the weather cools down)
Ive heard guys say to put some loctite on the threads to keep it from backing out again. Thats my plan as well