Small Engines (Lawn Mowers, etc.): lawn boy self propelled mower

Question
when I release the handle the engages and disengages power to the rear drive wheels
and try to back the mower up, the drive wheels seem to be locked; they won't roll

Answer
What is the model number of your mower?  The model number is a 5 digit number.

Many time the pins in the drive axle will rust and stick causing the problem you described.  Have you removed the wheel(s) and cleaned/lubed the drive gear(s)?

Only do ONE side at a time.  Often times there is a right and left side so DO NOT mix them up.

Eric