Small Engines (Lawn Mowers, etc.): Hard to shift tranny, craftsman mowers, craftsman model

Question
Hello,
  I recently got a Craftsman model 917.258522 lawn tractor from a friend.  I have ordered the owners manual, because I like to read such things.  I am having a problem with shifting the transmission.  It will not go into reverse, I can shift through the forward gears with difficulty.  I have looked for a fill or drain plug on the tranny and not found anything yet, but I am going to pressure-wash it this weekend to see if I can find anything.  If you have any suggestions, please let me know.

Answer
What a friend.  You have internal trans problems.  Rebuild will be 400.00.  Find another freind and pass it along.  In my family we do this with fruitcake at Christmas,  not Craftsman mowers.

This trans is filled with grease and there will not be a drain plug.