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Hi Everyone,
I'm new to this group and have come here in hopes of getting some advice on a problem that I am having with my 11 year old John Deere JA65 push mower. The mower starts and runs fine for about five minutes of mowing grass that is not overly long and on flat terrain. After five minutes or so, I can hear the mower blade start to slow down and continue to slow down until I can no longer hear the blade turning at all. If I move the mower off the grass the blade will very gradually begin to pick up speed but never really comes back to normal. If I disengage the blade and let it rest for a minute (like when I'm emptying the grass bag) and then re-engage the blade, it sounds normal again. Then, a few minutes later it slows down again. It seems to happen whether the grass bag is full or empty. During all of this the engine itself does not slow down. It's just the blade that seems to be having problems. My simplistic troubleshooting has included 1) changing the oil, sparkplug and air filter and 2) siphoning the gas from the tank and replacing it with fresh gas. I also checked the blade and it seemed to be fairly sharp. When none of those things helped, I took it to my local Deere dealer and they told me that the engine RPM's were "out of spec" and adjusted them. I also asked them to check the belts and they told me they looked fine. Unfortunately that did not fix the problem . Does anyone have an idea as to what I need to do to fix this mower? Thanks in advance for any help you can give me.

I'd sure revisit the belt (s) as a place to start. They may be glazed or worn to the place that you are experiencing these problems, especially after 11 years.:wink:

I'll side with benski on the belts,but on a side note, i have to wonder why the dealer mechanic could not see that (if) the belts were glazed and or loose.

Ja65 has a BBC (blade brake clutch) straight down the crankshaft to the blade, sounds like the lining on it is about shot. The transmission is the only part belt driven

see if this helps you -

Take the blade off and look where it meets the bearing - see if the blade opening for the bolt has been changed by an impact or getting loose .
I had a sears mower come in the shop like yours - craftsman uses the star pattern on the bolting mate Area - the mandrel was worn and the star was almost gone . The blades would turn fine then get loose . The blade is stronger than the mandrel set up - most inner bearings can be changed in just a minute - slips right out of the housing after taking the blade off and the pulley .
Remember you don't need an impact wrench to get a pulley off . I use a mini vice so it bites the pulley and hits the mower body so the bolt backs off easy .