It's time to summarize everything. First of all, please make sure that you know what you're doing before you do anything to your Ranger. The Ranger is a discontinued legend, so take your own risk and I take no responsibility about the accuracy of this project because there is a chance that not all Rangers are created exactly the same. And I believe, no two Rangers are identical.
First of all, I slide the balance dovetail to the focuser end, and then I can remove that small screw which acts as a stopping pin.
After removing that pin, you can remove the dovetail easily. Be sure not to lost any screws in the process. There're some plastic tip in the set screws and so the metalic part will not be scratched. After removing the dovetail, two more screws will be seen.
One of them is to hide the pin which guide the drawtube, the other one is to fix that dovetail saddle on the OTA. If you have done everything correctly, you can remove the whole draw tube slowly.
One I have removed that draw tube, I found it pretty long. On placing it side by side with my NGF-S, I immediately hope that I can use that NGF-S to replace that helical, and to custom made another draw tube (48mm outer diameter) to replace the original draw tube, by then you actually gives 2" capability (close to 2" actually) to the Ranger!
However, before I proceed, it's actually nice to check if it works or not by doing some feasibility studies:
As you can see, I placed that NGF-S immediately behind the opening for the drawtube, and then I inserted my 2" mirror diagonal and my 2" Pentax SMC XL 40mm there. I view through the eyepiece, and it's quite good... However, on adjusting the NGF-S through the whole range, it won't focus. Worst yet, it's on inner end, i.e. I cannot focus even if I'm using the shortest setting of the NGF-S... i.e. insufficient in-travel! If it's out-travel, I can always use an extension tube, or to make a longer drawtube, but now, there's no chance. To make it even worse emotionally, I believe it took only around 1cm or even less!!!
With 1.25" diagonal, it will work, but then it makes less sense to do so. It just gives motorized focusing, but nothing else. Frankly, I can cut the Ranger OTA a little bit on the drawtube side, but I hate to do anything intrusive modification since the Ranger is a discontinued legend, I don't want to kill it altogether.