Hi figarow, welcome to Outdoorking.

I'm assuming you start the machine with the cutter clutch disengaged - normally ride-on mowers will not start otherwise. I'm also assuming that the squeal begins immediately, when the engine starts - it isn't something that only happens when you step on the drive pedal.

My first guess as to what would cause a symptom like that, is a belt idler that is more or less seized on its shaft. The Greenfields have more idlers than most mowers, so finding out whether that is the problem, and if so which idler is at fault, is the tricky bit.

Here is an illustration of the parts of your mower, unfortunately scanned in very low definition so it is not especially useful:

[Linked Image]

There is a pair of idlers (Item 72) which guide the wheel-drive belt, and those might be a good place to start your investigation. You could inspect their condition, and perhaps oil them and see if that eliminates the noise.

Please report back - if that isn't it, we can look further. Also, there are quite a few experienced Greenfield owners on Outdoorking, any of whom might be able to identify the problem easily.