May be on to something. I just pulled engine top shroud off and when starter is energized, the starter gear that raises to mesh with flywheel teeth is getting hung up under a flywheel tooth and won't allow it to fully engage with flywheel. By bumping starter, it eventually moves flywheel just enough to allow flywheel and starter teeth to lineup and that's when engine turns over. Should starter gear be greased, or is there something else going on?
You can apply a very small amount of white litilum grease to the spiral which is called the bendix gear.
The teeth on the starter do wear as does the entire spiral gear mechanism ( Bendix ).
They are a replacement item Johnstone Automotive used to do aftermarket parts and most auto electricians should be able to swap it over for you.
If you decide to pull it apart yourself be very careful with the retainer as they are specific to that starter , not a replaceable item and a right royal PIA to remove and almost as hard to replace.
A long time Mar & Par type mower service shop might have some spare ones in the box of starter bits under the electrical bench but most glass fronts will just hit you for $ 200 + for a full replacement.