Chazb211 - I also have an older Craftsman, was mowing fine, stopped to pick up a branch, when I reengaged gear, movement was extremely slow. I changed out the tranny & drive belt and still have the same problem. I wish I had a trouble shooting guide for drive train. If you find an answer, please let me know. Extremely frustrating...

Hi,
It would aeem to be a tension problem; was there a scraping or some other sound previous to clutxghing th unit?
You gave no model, so I am stuck with that.
Peace,
Clarke

Can you give more details about what you did " I changed out the tranny & drive belt " With the ngine off engae the trans in gear and let the clutch out, reach under the engine and pull sideways on the belt. Can you pull it much sideways, I 'm thinking tension too.

Yeah, I found the solution! After ballengerb1 replied, I went out & checked the clutch. All I needed to do was adjust it & my mower is now driving great. So if anyone else has had this similar problem, look in your manuals or go online & find out how to adjust your clutch. If it does not release all the way after you put in gear - it is still applying brake and this causes the mower to move slower. Thank ballengerb1 - you had me look a little more & I managed to fix the problem.

Thank you criby also for responding. Mine was a 93 12hp Craftsman.