Small Engines (Lawn Mowers, etc.): 1990 White Lawn Mower, briggs and stratton, flywheel teeth

Question
I was given a 1990 White Lawn Mower with a Briggs and Stratton 15 horse engine over head valves. The engine turns over, but when the cyclender gets on compression the starter cannot turn the engine over. The starter just hums and gets hot. Any help you can give me will be greatly appredicated.

Answer
 Hello Ken:

 Lets do a few things and find the Cause of your Problem. 1- Remove the Belts from the Engine Pully. Does this help?
2- Does the Starter Turn the Engine when Jumped Straight to the Starter? yes/no
3- Check the Flywheel Key. Is it Bad?  yes/no
4- Is the Starter Mounted Properly.  yes/no  The Starter Drive Gear should not set more than 1/2 to 3/4 into the Flywheel Teeth.
 Go through these and get Back to me with the Results.
 Hope this Helps

 Good Luck

 Respectfully

 John