I was mowing a yard for a customer using her mower and it just stopped moving. I tested the clutch/brake pedal a few times and dis-engaged and re-engaged the drive mechanism and nothing happened.

Don't know doo-doo about lawn mowers. Know a little about cars. Have replaced and/or adjusted a few clutches in my life and know how it goes when they fail. So my suspicion is that is the problem. It continues to run and run well, it just doesn't drive the mower.

I don't know the Model Number and I think it's a six speed.

I guess my question is: am I on the right page thinking it's a clutch/drive thing or is it something else? There's a pull-pin in the back that disengages the brake and makes it possible to push it by hand and that seems to work. Looking underneath it looks as though all belts are whole, connected and tight and the clutch/brake mechanism seems to be working when I work it by hand.

A person at Craftsman Help Center suggested that it may be a switch mechanism under the seat malfunctioning.

Any thoughts? Any chance it's something I can fix myself.
I know car clutches need to be adjusted from time to time.
Is it possible that it's never been adjusted?
It's a five year old machine.
Maybe the clutch is just worn out.

That Sears person was thinking the engine stopped. Your engine is running but there is no movement, right? Takes two people and one flashlight to do this checking. Driver starts the engine and keeps the drive in neutral. The second person looks up from between the mower deck and bottom side of the frame looking for the drive belt and spring loaded tensioner pulley that will move several inches when you release the clutch. Does the pulley move and put tension on that drive belt? If it does and the large drive pulley starts to spin you may have a broken key on the drive pulley allowing it to spin on the transmission shaft without turning it.

You're right, the Sears person assumed the motor died. I informed her that it continued running. She said that switch operates a number of functions, one being the "transmission"
Function.

I'll give your test a try and see how it works out. I'll have to round someone up to help me.
It's about 20 mile out in the boonies and the homeowner lives about 100 mile away. But there's a helpful neighbor that can may lend a hand. Thanks for your help.

Sears person is still off base. The switch is linked to the trans but not the way she leads you to believe. The switch can control a few transmission operations depending on the year and model you have. The most common is not allowing you to start or operate the tractor when its in gear or reverse. The newest Sears Tractors have a additional position on the key swicth that allows you to have your blades engaged while you back up. I think this new options is called ROS by the Sears folks.

Okay then. Thanks for the clarification. I won't be out to that job again for another week.
So I won't do the test until then. I'll post my results when that's accomplished.

I know lots of folks who swear by Sears but I've joined the group that swears at them. I have the 2005 version of your same tractor and have had poor luck with it. I started backfiring so I cleaned the carb, then had to rebuild the carb, still backfiring. Several of us eliminated all other causes such as a electrical issue so now I'm putting on a new OEM carb for $200. Not what I wanted for a 3 year old tractor that I got for under $1k. Good luck, Bob

Gotcha. From what I've seen on this website a lot of people have had problems with them.
She's gotten five years out of this thing though so I guess its paid for itself, but I don't think I'd buy one myself. Her neighbor has a Scotts/John Deer which is a lot older but it does a better job of mowing and served as backup that day.

I like Craftsman for hand tools, especially Socket sets and the like. Prefer Black and Decker for small power tools. My dad was a life-long auto-mechanic and when he wasn't using Snap-on he was using Craftsman.

When I do lawns I tend to use the customer's mower, and when you lift that engine hood you find one common name. Briggs and Stratton. That's a selling point for me. Don't know if this Craftsman has it, but it seems to run fine. Just don't want to move.
I considered getting off it and just kicking it in the but I've already fractured that foot once... didn't want to do it again.

I agree reagrding their guarantteed for life hand tools. Seems like they have cheapened everything else to the point that you might as well go to Menards or K-Mart. Oh I forgot they own K Mart.

The pull-pin in the back that dis-engages the drive indicates a hydrostatic (auto) transmission. If pulling this enables you to push the tractor, my money would be on a sheared drive key in the pulley on top of the trans (or something even more obvious such as a broken/off drive belt.

The term 'clutch' is too grandiose for what's actually fitted - the pedal simply slackens off the belt. With the auto trans, there's no reason ever to use it unless you're mowing on a steep hill.