husqvarna mowing problem

[windyhill]

I have an mz6128 zero turn mower.i bought it new in 2013.The deck started slowing the eng. down,so I checked the spindles and idler pulleys.Ireplace the right mandrel with a new assembly,(it turned hard).this didn't help. can anyone tell me what could cause this problem.mower has less than 100 hrs.

 

[ILENGINE]

Assuming a twin cylinder, is the engine running on both cylinders, that will cause a major slow down under load.

 

[windyhill]

I will have to check that.it does sound different-louder.i also was told the governor might be hanging up