This is a movie of a thrust bearing check posted by 928sRus. It is hosted so people have an idea how to properly check.

928 Owners are always asking me about TBF on automatic 928's from 85 to 95. There are lots of theories why this happens and I do not want to go into the various reasons. Suffice to say - ALWAYS HAVE THE END FLOAT OF THE CRANKSHAFT CHECKED BEFORE YOU BUY AN AUTO (ROGERBOX) 928. I always hear that the flex plate clamp bolt has been removed and the forward pressure on the flex plate relieved. This is only a small part of the check. It is imperative to measure the end float of the crank in the block. Basically the backward and forward movement of the crank. Obviously there needs to be some free play otherwise the crank will not turn. Factory spec is approx. 0.007" (0.18mm). Up to 0.016" (0.40mm) you are OK but anything beyond that means you are into TBF and terminal damage to the engine. The attached video shows a very bad case of TBF at 0.070" (1.8mm). Which is the death knell for this engine. Make sure everyone knows that the end float of the crank is the important criteria and not just releasing the flex plate pressure. Roger 928sRus