Deere 777 power loss
I just bought a used 777 ztrak for residential use on my three acres. It has 2400hrs. The problem I'm having is a powerloss while cutting.
If I'm cutting a run of approx. 250 feet when I start to mow I'm discharging the clippings from 8 to 10 feet, but by the end of the yard I can hear the mower deck slowing down and the clippings are only going 3-4 feet out of the chute. Once I make my turn, the deck speeds up again and the process repeats itself. I'm not experiencing any backfire, stumbling, or fuel starvation symptoms. Just a gradual power drop as evidenced by the shorter clippings discharge and noticeable drop in blade noise.
Here's what I've done/know about the mower:
FD750D liquid cool
New Deere blades from the dealer
Deck is level left to right and just over 3/8" pitch front to back.
New 93 octane gas
New fuel filter
Greased deck spindles
Motor idles smooth at fast, mid and low throttle position.
New motor oil and filter
New hydro oil and filter
Tonight I checked the valve lash but did not have a chance to adjust it. Left side was .008 for intake and exhaust. Right side was .008 exhaust and ..010 intake. Could this be the source of my power loss or do I need to look elsewhere?
Thanks for the help.