It is not a difficult process to remove and reinstall a rotor. First you need a good set of gunsmith screw drivers not to mess up the screw heads. The end of the rotor on your vintage will have a split nut on it and will require a screwdriver. These can be purchased or made. I prefer to make mine by hand and not with a power tool. There is too much heat from a power tool and you loose the temper on the bit.
The hardest part of the whole job is not having 3 hands, that is where a good gun vise comes into play. You will need to remove both the forestock and possibly the butt stock. Properly secure the rifle to work on it. Some of the early rotors had a straight slotted screw (like the 25-35) but I believe that all of the 300 savs were late enough to have a split nut on the end facing the forestock. Turn the split nut slightly counter clockwise as this will take the tension off of the carrier spindle retaining screw (small screw on the left hand side above the cartridge counter window). While taking the tension off the rotor then the carrier retaining screw can be removed. This is where the butt stock will probably have to be off. To remove the rotor normally I have to push it from the rear to get it through all of the years of crud around the cartridge counter window area. Putting it back in can be a little tricky. Insert the rotor into the receiver. The rear of the rotor carrier spindle goes through a rear hole in the receiver and the cartridge guide is supported by this end of the rotor carrier spindle. The largest fin on the rotor will rotate counter clockwise until it comes up against the cartridge stop. Once it hits the cartridge stop is when you start loading up the tension on the rotor. When you have the rotor out you will notice 4 grooves in the carrier spindle above where the numbers are located on the brass rotor. This is where the carrier spindle retaining screw rides. When you adjust the rotor tension if it is too tight then you can't get 5 rounds in, if it is too loose then the last one or two won't come up. The only way to test the tension is by trying to load the rifle. I only use cartridge proving dummy rounds for this and not live ammunition. It doesn't have to be wound tight, just enough to get the last round out. It is easier on the spring. So when you get it to where you feel the tension is right that is when you put the carrier retaining screw back in. You may have to adjust slightly one way or the other to find the slot. If it turns out to be too loose or too tight, then just adjust by 1/4 rotation at a time trying out the tension again.
While apart it is the time to clean out the receiver and clean up the rotor. I will use a little oil and some very fine (800) sandpaper to clean up the area where the rotor rides inside the receiver. I prefer to just clean the rotor by hand and not get carried away with polishing it up. I know that it can be brightly polished but for an old gun I want it to be clean and not new looking.
Hope this helps.
. I too would be very interested in information on these rifles.
