2009 Fastrak steering adjustment help needed

Hi guys,
I've got my mower running great now but have a problem with my steering.
I've found that the left hydro does not run as fast as my right hydro. Therefore,
if you keep both steering levers equal, the unit will track to the left (left turn).
I've purchased a laser tachometer off of ebay to try and help measure the speed
of each tire. I'm not worried if it's terribly accurate---just consistent. I hope to get
both hydros adjusted to the same speed when the steering levers are adjusted to
the full forward position. Is my thinking here correct?

So, I am asking if there is a written procedure for this adjustment? I can see the
linkage adjustments that are available under the seat area. If there is no written
procedure, can you provide insight on how to approach these adjustments? I don't
want to screw this up.

Thanks much for this great site. I've read so much here and found it very helpful.
By the way, my model # is : 926519

Thanks,
Harry