Re: 1998 Merc 200 EFI Starter is spinning but not engaging?
First, clean the shaft that the Bendix gear slides up on. WD-40 is good for that. Then give it a few drops of light oil. 3in1 is okay, but Singer sewing machine oil is better.
Give her a try.
If she still merely spins without engaging the flywheel, remove and clean all connections in the big battery cables.
Let us know what you get.