Off Topic: Visual Spinning Of Engine Fan blades

I posted this note in another forum, but was wondering if anyone had an explanation.Basically, there is a big difference between the way the PMDG, LevelD, and other engine fan blades spin in FSX, and how they used to spin in FS9. In FSX, they look like they are shaking back and forth. More of an agitating (washing machine) look, than circular spinning.This is very noticeable on engine shutdown. Rathar than a nice decline, and spool-down effect they "shake" until they just stop dead. In the FS9 version, you would see the gradual spool-down, and the fans spinning gradually down until stopping... even windmilling a bit.Is this just an FSX "feature", or is there something that can be done to improve the look?Thanks in advance,John