I am having a 740B dumper with parking brake problem. The parking brake hold or slowly disengage when I disengage and try moving it. In order to disengage completely, I have to accelerate the machine at neutral ( no gear selected) before it is released. Then I put it in Drive to move further without any issue. If not it continues to hold why driving. This trick has to be continue anytime I hold the brake in order to Drive freely.