I have a 1950 Buick with a Dynaflow. The trans engages and runs well. The problem I have is that while driving, over time the shift lever will slip down into low. On a really bumpy road, it happens much sooner. Being a novice to the Dynaflow, is there an adjustment to tighten the shift lever, or is this a function of some other issue? Appreciate any help you can provide. Thanks in advance.