开云体育

Take a look at a photo I just posted under Alex P. It shows in detail the cut in the spur gear.? ( at least mine )
Only in the central portion is a radius machined which matches the circumference of the worm.
On the upper / lower transitions between this and the 'flat' portion of the main machined cuts is an Edge.

IF the worm is above or below perfect center, it will engage that Edge .. for better or worse..

-ap