Small Engines (Lawn Mowers, etc.): gear assembly walk behind lawnmower, drive gears, gear assembly

Question
I had trouble with my craftsman walk behind mower model # 917.378493 where the front wheels were no longer pulling. I changed the belt but it didn't help. I noticed the pulley wasn't turning so I changed the gear assembly, assuming it was bad. Now the shaft on the gear assembly & the pulley turn great but the wheels are not catching (I also put on new front wheels). The gear pinion & wheels spin freely. I tried to put everything back together the way I took it apart. Can you tell me what I may have done wrong to cause the wheels to not catch?

Answer
Hi  mark

Here is web site for manual and parts diagram
http://www.hammerwall.com/Download_Manual/8635/

please check that pawls for each drive gear in r/h and l/h wheel drive gears are free and are engaging and have not been fitted incorectly?   see page 36 for  diagram

is the drive cable pulling the lever on the top of the box into engagement properly?
it is not likly that anything is wrong internally in the box , check out drive gear pawls 1st  
they are part number 21 and 22  in the  drawing on page 36  

have a look at page 36    from above downloaded manual it has breakdown of gear box and drive system as well as engine

from what you have told me sounds likly that may be where problem is


take a look  , let me know what you find

cheers  Paul