The problem is simple, using the handbrake mountings onto the floor and the handbrake is positioned so low one just cant reach it nomatter how hard one pulls against the 4 point harness.

Solution tip the front or raise the whole thing. We chose to tip the front. Whichever method you use the pull hole for the clevis pin is now not under the floor. We have mounted a pulley under the floor and problem solved. However you will find the geometry trickey. Another problem may be the seat missing the handbrake.