Back Gears: The screw on the right side (chuck end) is to tension the shaft so that it won't come out of gear, but loose enough to still engage it. The one on the left is for adjusting the engagement of the backgears. To adjust it, loosen it up and engage the gears to where you want it(shims, feel, what ever method you use), then screw in the screw untill it touches. Disengage the gears and engage it to the stop and test it. You may want to tweek it from there. The screw is the stop. It hits a slot in the ecentric that limits the rotation of the shaft. Engage the back gear, then back off the screw, then engage it some more. Do this untill you are happy with the backlash. Ted Pflugner *************** To remove the back gear, the taper pin on the right side of the back gear has to come out. Roll the back gear so the little end is up and tap it out. Now take out the square head bolt on the right back underside of the head stock casting. The one on the right side could have a spring and a bronze shoe under it. The one on the left is a stepped set screw with a nut, this is the adjustment setup for the back gear clearance. Take these two items out of the casting and after you slide the right side bushing out of the casting the back gear handle with shaft will slide out to the left. Dont let the back gear drop."-))) . Dennis Turk ************** The top oiler there is only a square head set screw to secure the right back gear shaft bushing. There is no spring or plunger to adjust the resistance to rotating the back gear bushing. The top oilier head stock has a spring loaded plug under the shift handle on the left side of the head stock. Many times these are not noticed until you remove the back gear assembly and get lost. This plunger and spring are what give the back gear the resistance so the back gears do not disengage while running. On the side oiler the right bushing is taper pinned to the back gear shaft and the top oilier version is not. In the side oilier version the right back gear shaft bushing rotates with the back gear shaft. The spring loaded plug under the right square head set screw is what is used to give an adjustable resistance to keep the back gears from disengaging. The back gears are the same, though the side oilier back gear is about 3/16 shorter. This was done so the right side bushing could be made longer. and this added length is were the taper pin is you have to knock out to remover the back gear assembly on a side oilier head stock. I also think the side oilier busing on the right side is larger in diameter than the top oilier version as this was needed to secure the taper pin in the bushing. The main problem with the top oilier head stock is number one the soft spindle and the fact that you cant adjust the amount of resistance to disengagement of the back gears as its fixed by the factory plunger under the shift handle. You will also see that the shift handle itself is different in that it has a flange that rides on the spring loaded plunger seated in the left back gear support part of the head stock casting. This is a blind hole housing the short spring and very short rounded head plug that rides against the flange on the back gear shift handle. Note that the 10K back gear is different yet. SB shortened it again to make room for the taper pin bushing in the new enclosed head stock casting that had just a little less room than the open 9 inch casting. Dennis Turk **************