Hydro-Gear 618-0319 knocking sound

[Marksmower]

Hello out there. I did some slow speed heavy cutting for 8 hours straight after returning form vacation and now I have a knocking sound coming from the rear gear on my CC LXT 1050 with Hydro-Gear 618-0319 transaxle. Everything still works fine and no problem with movement and no leaks from the unit with 430 hours. Never changed axle oil.
Has anyone else had this happen or know what's going on?

 

[Auto Doc's]

Check the input drive pulley. Likely it has hammered the center splines and is now loose on the shaft. It may need the shaft replaced which will require teardown.

 

[Marksmower]

Thanks. Checked the pully and its tight. Oil level is about 3/4 down from top and looks clean. This knock sound is repetitious and varies with input rpm and is coming from within the trans case. No change in the sound when turning so I think gears are ok.

 

[StarTech]

Okay try pin pointing the problem. Put the transaxle in bypass mode and release the clutch with the engine running. Basically is the noise still present? If so then you probably have bearing failing in pump/piston side. If only present while you are moving around then it is likely in gear train side of the unit.

Also double check the input pulley v groove to see if any thing is lodge in it.