Unusual Braking Problem

[evdama]

Red rubber grease on ebay not expensive and available in tiny little pots so its not sat on the shelf for your great great grandchildren to have to take to the tip.

[smutts]

Red rubber grease on ebay not expensive and available in tiny little pots so its not sat on the shelf for your great great grandchildren to have to take to the tip.

Nail, Hammer, Head.

There will be about three 500g pots of well rancid red rubber grease in my death skip. 
These will be fished out by the undead "that will come in handy" skip divers.

[evdama]

Oi!
Less of the undead 
Most of my projects are funded by clandestine skip harvesting 

[Drummond]

When a brake will not release, the first thing to do, is slacken the offending calliper bleed screw.

I second this method. Additionally, to rule out ABS, pull out its fuse when the fault is on. That’ll prevent the electronics acting up. 

My bet is still on hydraulic or mechanic side. Internally swollen brake hoses, or maybe master cylinder not fully releasing.