I have a C20b of the same era (60's) and the brakes seem to hang going from neutral into gear, or between forward and reverse, throttle just slips the converter until the brakes release then it jolts, any time you press the brake pedal and release it does this. It sounds like this problem described with the inching "slave cylinder" above, and yes two brake lines go on top of the trans into a body. I can post pictures if it helps, any guidance on what i should be looking for to fix this problem?

My forklift is basically in-operable because of this issue, as i don't want to abuse it when there is clearly something going on.