Big respect for using the search function. When I had a sticky cable I took it off, stuck one end in a coke bottle of light oil, taped it up and hung the bottle upside down to let the oil run down into the cable. This can be bad cause oil holds dirt and scratches the plastic cable over the years BUT it passes mot. I seen on a post of morgeys if the handbrake lever on top of the caliper sticking cause its dirty/rusty. Give that a good clean first and compare it to the other side.