Just fixed a similar problem. Handbrake was getting very unreliable, so I decided to take a look. One of the cables appeared to be seized due to a very tight turn becoiming dry and full of crud. But this did not solve the problem. After a bit of head scratching I discovered that the bolt (sorry I don't know the technical name fot it) that the handbrake lever swivels on, at the rear of the lever where it meets the floor, had fallen out! I've never heard of this one before! OK it turned out to be a quick and easy fix, but how close was I to seeing it roll down the road without a pilot on board?