I've just bought a Mk 3 estate with the driver's side handbrake not working. The lever on the caliper was pulled fully forward and jammed. This made the handbrake lever inside the car pull all the way to the top. I put some WD-40 on the caliper lever and worked it back and forth to try to free it up. It didn't appear to help. I bought a new caliper but before I got a chance to fit it, the handbrake lever on the caliper freed itself off and it's now working fine.