2001 Lesabre Transmission jerks hard

In 2008 reverse went out in my 2001 Buick Lesabre. I took it to the Buick Dealer and they replaced the old Transmission with a new rebuilt one. The rebuilt one worked fine until late 2009 when it would, after being driven for about 50 or so miles continiously, the trans would shift very hard and develop a whine. After sitting over night this would always stop until I drove it on a short trip again and then it would start doing the same thing. I took it back to the dealer, in April of 2010 and they diagnosed it to have a bad coil and needed plugs and wires. They charged me $97 for the diagnosing and wanted $600 to replace the said parts. I said, no thanks and did the work myself for less than a $100. Only problem is, this did not solve my transmission problem. I still have the hard shifting and whinning when the transmission gets hot. We have babied this car and it only has 70K miles on it. the fluid is a clean red and has no burnt smell at all and is right up to the full mark when checked. There is no leak or blow by. Does anyone have any suggestions?

Nice mis-diagnosis on their part, how does hard shift and whining equate to a tune up! This is usally caused by the pwm solenoid sticking in the high line pressure position, to confirm a full trans scan should see what the issue is.

Exactly! I hate getting ripped off. Where would a guy go to get a scan and a honest diagnosis? If it is the solenoid, would the only fix be internal transmission work? What gets me, I drove the car this morning, went about five miles and the darn thing ran and shiffted perfect.
At the time of having to have the transmission replaced, this was my wife's car, and her only mode of transportation. It was a quick decision and a very wrong one! I'd bet there was not much wrong with the original transmission. I don't usually get taken like that, having been in the auto parts business for 25 years, but that is one time I failed. It hard to believe that an old established dealership such as the Buick place, just replaces parts and has no one that can repair them, as in my days.

Any quality trans shop or the dealer has the proper scanner to check that issue.