[rotorwrench]

The end play adjustments are the only adjustments that can be made on this type. The end play is important on straight cut worm & sector gear drives. It has to be minimized to get the best possible backlash of the set. Sadly, there was no other adjustment to place the sector gear closer to the worm gear on these early units. If there is too much backlash on center then the worn parts have to be replaced with new or serviceable parts. The free travel should be no more than 1" to 1 1/2" of rotational play in the steering wheel with the pitman arm locked. The good thing is that the parts aren't too difficult to replace and all are available as far as I know. They are a respectable unit as long as they are within the range of serviceability.

A straight cut worm and sector set that is worn on center, could be too tight off center even if it can be adjusted by machining methods. This is one of the reasons that the Gemmer-1 2-tooth design was adopted later. It was designed to be loose off center so as to keep better wheel geometry during turns. It also allowed for some compensation for gear wear on center as long as the gear faces are still smooth and free of spalled out pitting. It's easier to turn as well.