I have a 1984 190E 2.3 that is lossing transmission fluid, but I can't find where. It is not leaking in idle, only losing when you drive the car. I have been told it could be the modulator valve, which is inexpensive, but I don't have the money to pay for a diagnostic to make sure. Is there any way that I can confirm this myself? Or is the person who told me that just an idiot to start with?