Small Engines (Lawn Mowers, etc.): Murray 21hp drive disconnect, transaxle, linkage

Question
Murray Select 465602X8D 21hp 46"
i cannot push the mower because the transmission will not disengage.  the automatice drive disconnect lever under the seat has no effect on the transmission.  by watching the linkage on the transmission as i move the lever i notice that the disconnect arm on the transmission does not move when the lever under the seat is shifted; so, i put a wrench on the disconnect arm and turned it ~10 degrees in either direction - still no effect on the transmission.
Any thoughts on how to disengage the transmission so that the mower can be pushed?
Thank you!

Answer
 Hello Steven:

 This is a Hydro Transaxle. If the Pressure Release(Disconnect) has Failed, then you will have to Dolly the Rear of the Mower or Drag it. Sorry. Hope this Helps. I am here if you Require more Assistance. Thanks.

 Good Luck

 Respectfully

 John