Small Engines (Lawn Mowers, etc.): MTD Yardmachines stuck in gear?, hp briggs, rear wheels

Question
When trying to mow my lawn this past week, I noticed that my MTD Yardmachines riding mower wouldn't start.  I don't know the model number, but I know it's a 12 1/2 HP Briggs engine.  I believe it won't start because its stuck in gear.  When I try to put it in neutral and push it, the rear wheels are locked up.  It has a safety that prevents it from starting while in gear.  I've checked the solenoid and starter, neither seem to be the problem.  I flipped the mower and I noticed that there was alot of grease coming out of the rear end, but no visible signs of damage or cracking on the case.  Do you think the gears are seized from lack of lubricant?  Any ideas?

Answer
 Hello Chris:

 Remove the Transaxle Drive Belt. With the Shifter in Neutral Turn the Pulley Located on top of the Transaxle. Do the Wheels Turn? if Yes, then Something inside the Transaxle has Frozen/Stuck or Broken. **Provided this Isnt a Hydrostatic/Hydromatic Drive Transaxle.** It Does have a Safety that Wont Allow the Engine to Start while the Transaxle is in Gear. Hope this Helps. Let me know what Happens, Please.

 Good Luck

 Respectfully

 John