Small Engines (Lawn Mowers, etc.): John Deere Sabre transaxle, transaxle not shifting

Question
I have johndeere sabre 1546 with gear drive with five forward speeds.  It is very difficult to shift from gear to gear.  The linkage seems fine.  What should I check and how can I repair?? Thanks

Answer
Usually if the linkage is okay it's the drive belt not releasing fully keeping the input under a little torque.  Oftentimes the idler that tensions the drive belt isn't moving through it's full range due to rust, dirt and grass clippings.  Check that and let me know what you find.  If it's not that, I'll need the make and model number off the transaxle.  There should be a plate or sticker on it.  Thanks, PK.