nipper

Thanks, jrtrebor.  Now your first reply makes sense - you had it nailed right away.  I misunderstood what you were talking about, and now it makes perfect sense.  I just ordered the spring (couldn't find it at the local hardware store or Home Depot).

Alright - I think there's a light at the end of the tunnel!  I'll give this a go and see what happens.  Thanks, guys.

Update:

I went back and looked at the pulley again, a little more closely (it's a little tough to see).  It looks like there is an arm attached to the arm that the pulley is attached to, and that arm has a hole in it where it looks like a spring should go.  Could this be where my broken spring is from?  If so, what does that spring attach to?

First, let me say that the people on this forum are incredibly knowledgeable and helpful - awesome!

I tried some of the suggestions that have been posted.  Here's what I've found:

First, when I tipped the machine forward, the wheels were able to turn freely when in neutral.  When I then put the wheels back on the ground, I got the same result.  Turned about a 1/4 revolution, then stopped. It just doesn't have the power to turn the drive wheels.

After taking off the belt cover, I noticed that when I engaged the drive clutch the Attachment Drive Idler Pulley wasn't engaging (see pic below - the pulley on the bottom-most left).  I believe that pulled is supped to press on the belt to create tension and turn the plate. It seems that some sort of linkage to this pulley is either broken or stuck or something.

Thanks, carlb.  I have a dumb question - how do you put it in Neutral?  There is no neutral on the gear lever.  Do you mean to just not engage the clutch?

The weird part is that it engages the drive wheels and it moves about a foot, then stop turning.