The chatter is most likely 'belt slap'. Most Variable Speed and Personal Pace mowers do this to some extent. Check your owner's manual for 'how-to' use the mower - you have to make sure it can coast forward when coming to a stop before the clutches release for a pull-back. It can go either way for you; one, you never get used to it and hate it more and more, or two, you adapt to the needs of the machine and learn how it wants to be controlled.
Detail of stopping for a pull-back; you stop walking, keeping your arms locked in position - the mower coasts forward as the handle returns to the top - the clutches should now be released for the pullback.
There must be free-play on the sliding handle, about 1" or a little less of travel, or the clutches cannot ever release. Get the needed free play by adjusting the amount of naked (unsheathed) drive cable housing visible on the operator's side of the cable clamp. I forget which way is which, but you'll find out soon enough after loosening the bolt.
A quick check for a tight belt/need for cable adjustment; on a hard surface with engine running, raise rear of mower (without pushing down on handle) until rear wheels are clear of the surface - they should not be turning. If they are turning there is not enough free play on the sliding handle.

To increase the free play on the handle (which, of course, decreases belt tension), pull the cable away from the mower after loosening the bolt.

My experience is based on two different Toro PP SR2 units.
* oo42 (2001 model)
* oo36 (2002 mod.)
I used both 5-6 days a week full time in LCO and they have some awesome durability and capabilities.
With this said there weakest points are as follows:
The rear ends wear out at the either right or left side depending on the way you most turn.
The release clutches do not always work and there fore you feel like your dragging dead weight all day.
They wear there wheels out quickly.

Great machines. I learned to adapt. I chose this season (last week) to purchase the Snapper mulching unit. The dealer sourced not Sears.

C.

Thus the advantage of front wheel drive self propelled units . Just lift the front wheels when req'd in a hurry.
Fortunately still in good enough shape not to see the need for self propelled....yet ! Good Post Eighteen . I to lean towards Mulching Style Mowers .

There is no advantage of any kind to front wheel drive mowers. You turn a rear wheel drive the same way as a FWD except you let go of the drive-control bail or manipulate the Personal Pace as needed to stop the drive as you turn. It is simpler for the operator to just pivot without even releasing the drive on a FWD, but the trade-off for that instant of simplicity is a fragile drive system that wears out the drive wheels annualy from wheel slip, and plastic gears that wear out fast along with poor performance going uphill and when bagging (more wheel slip as the front end gets 'lighter'). I'm not too sure about the 'rear ends' wearing out from turning. They do require cleaning and lubing on the axle end gears/clutches every year. Plus, that poster said he was using residential-quality mowers in a commercila lawn-care operation. That amounts to 500% more wear and tear than a once-a-week residential application in any given time period. Since the Super Recycler is not sold as a commercial mower, you can't misuse it as such and then complain about things wearing out. It is true, however, that on some PP applications the wheel clutches are stubborn in releasing which can drive you crazy with the hard pullback, particularly when you have to pull back against a slope. Apparently some of them are no trouble at all while others require very deliberate manipulation to release.

Sax: My post was to the original poster no mention of Commercial usage , just a dead cow inference towards dragging a rear wheel drive back wards. Sorry I suppose I should have clarified that. Yes I understand the difference of manipulating the manual bail but choose not to utilize it on any of the Craftsman Models that I have used . I just lift the front and back up or turn as req'd , then lower the front gently and allow some wheel slippage to reduce front drive component and belt wear . As far as rear wheel unless it has posi track , it will cause differential gear damage or as I have seen cheap clutch wear during repeated turning. I have always found rear wheel drive more work than overall benefit (traction) for my needs , then I don't have traction issues (hills)to deal with . Therefore I do not favour Self Propelled to begin with . Just something else for the Dealers to make money on . If I cannot propell on my own than its Tractor or Zero Turn Time Baby !