My 1991 740 base model has been having inconsistent starting issues lately. When I turn the key to ignition the engine/starter squeals, but does not turn over. At first we thought this was a starter issue, but because of the inconsistency we think there may be a few "bad teeth" on the flywheel. Has anyone experienced a similar issue and fixed it by replacing the flywheel? Or is there something else to try first?

 

What kind of "squeal" are you talking about? Is the starting turning but not engaging the flywheel? If this is the case you need a new starter, the solenoid is not shooting out the drive gear into the flywheel. To make sure, take out the starter and bench test it, and look at the FW teeth while you are at it.