The process of diagnosing a transmission problem is very tricky. You really need to know how to take one apart and put it back together to guarantee you can diagnose one properly. The question is always whether or not you should pay for diagnostic time. Of course the answer to that is not simple either.
Beware of shops in OKC that offer a free internal inspection! This process takes a fare amount of time and labor. What they will charge you for if you refuse any corrective service, is to put the transmission back together and install it in your car. A reputable transmission shop OKC will offer a free preliminary road test and a visual inspection of your transmission. That simply means they drive the car and attempt to replicate the symptom and look at the outside of the transmission unit to give you a good first idea of what is going on.
Unfortunately, if neither of those reveals anything you have to agree to pay for some extended diagnostic time. Fortunately, many times an experienced diagnostician will know immediately if the problem is not inside the unit and can save you a lot of time and money!
Any reputable shop will charge you for an internal inspection service. This service does include removing the transmission from you car and completely disassembling it to find the cause of failure. Again, there is a fair amount of time and labor involved in performing this task. What less reputable shops do is give you a price without explaining the details. Most shops will give you a price based on one of the popular labor rate guides . Some may average it out and give you a flat rate.
Either way you MUST ask them how they arrived at the inspection price. Less honest shops will set the hook by giving you a very low inspection price and then once the transmission is apart, you are at their mercy. Once your transmission is out of the car and the parts are in the shop you have a mess. You really don’t want to take a transmission unit that is already broken down to another builder unless absolutely necessary.