@Jay C posted:This is probably not relevant and, most likely isn't the issue. Earlier models had axle gears that were 10.5mm in diameter. Later models have 10mm. Is it possible the model had the newer gears? Other than diameter everything else is identical.
That sounds pretty important to me! If you change the worm wheel but not the worm, and the mesh isn't perfect, I'm not surprised that you'll have poor operation and noisiness as described in the original post.
"Other than that Mrs. Lincoln, how did you like the play?" 
