That caliper is a PAIN to get the pads in correctly and still "sliding" enough to work properly
The "spring loaded" bracket can be the problem , that and the caliper is a single piston job as well
Both those could explain the worn out V unworn pad thing.
Tin
I got the mounts to put aftermarket brake calipers on your springer either 2 piston or 4 let me know if you want one will be at most half of what a shop asks
smut