Hello, I have a jw case mated to a big block Ford with a chance bolt together converter and in some initial testing of the car I noticed the wheels creep forward while on the transbrake. I checked the linkage and it's perfect. I checked line pressure at the servo and get 195 psi in 1st and 2nd and when I engage the transbrake pressure drops to 50psi. Car goes into reverse on the button but takes it a few seconds. I'm sure it's from the low pressure. My question is what else should I check and what could my problem be? It's a band new case with new clutches and band. Not sure what brand valve body or transbrake solenoid. I'm a total newb when it comes to automatic transmissions and my first glide with a brake. Thanks in advance for your help.