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Hello everybody. I need a little help with my John Deere F620 front mower. It recently started having some issues while mowing. When you start up the mower deck, the blades turn fine, but it sounds different, has no power, and acts like it’s putting a large strain on the motor. Many times if you lower the throttle a little, you can hear it start running great and there’s no issue. It started doing this more and more and now does it all the time and lowering the throttle is not working. To me it seems like the electric clutch is slipping? New clutches are about $300 so I want to troubleshoot before just replacing it. Any thoughts?

Take the belt off and check all the spindle and idler bearings. Don't just spin them, put pressure on them while turning slowly feeling for any grittyness.

That’s a great idea. I checked the spindles when this first started happening but I didn’t take the belt off. I just spun them and they moved freely. I also thought if one was bad it would get really hot. I felt all of them after running for awhile and they all felt hot. I just assumed that was normal. I will check them with the belt off. Unfortunately I do not have time until Monday. I will update after then.

You shouldn't be able to free turn the blades as the pto clutch brake should holding back on turning. The spindles and idler bearings are check out fine then the electric PTO is the problem. They do wear out.

Seems odd that it smoothes out with the throttle cut back. Is the motor running on both cylinders when loaded up? Might try a new set of spark plugs. They do go bad these days.

Alright, so I finally got a chance to tare this apart. I believe both idler pulleys are bad. When I pull them off and spin them on my fingers, I can hear a loud grittiness and one of the pulleys was difficult to spin. I also replaced spark plugs and it is running smoother now. I hope that does the trick. The spindles do have a little bit of noise when I spin them, but I really don’t want to replace them. I lubbedth up really good and hope it will be alright.

Ry Guy said:

Alright, so I finally got a chance to tare this apart. I believe both idler pulleys are bad. When I pull them off and spin them on my fingers, I can hear a loud grittiness and one of the pulleys was difficult to spin. I also replaced spark plugs and it is running smoother now. I hope that does the trick. The spindles do have a little bit of noise when I spin them, but I really don’t want to replace them. I lubbedth up really good and hope it will be alright.

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Yep, you want all spindles and pulleys to spin free with no grinding or noise!..Of course new, grease packed parts will be stiffer but smooth because of packed full of grease!

You do know that rebuilding the spindles before they fail completely is more cost effective; unless, you just like giving JD extra money? The bearing can gotten in generic but is the seals that usually has to come from JD.

Double up on what Star has just said.
A collapsed bearing cage can trash the housing taking the belt and the blade with it.
Do not try to remove the spindles from the deck as usually the mountings will break off.
Remove the top nut & pulley then "tap" out the shaft
The bearings si on shoulders so the top gets knocked out from the bottom & visa-versa, although the bottom will oft come out with the shaft