Maintenance tips for the Corona 3
The ribbon should be 7 yards long and 1/2" wide. Longer ribbons can cause mechanical issues. It should feed from the rear of the right spool and the front of the left spool because both spools draw the ribbon in a clockwise direction. The Spool Nut should only be tight on one spool or the other (one loose and the other tight) or the machine will freeze up.
- Loosen or remove platen set screws
- Loosen or remove platen knob set screw
- Push or gently tap right end of shaft until you can grip the left end and pull it out
- Lift right end of platen up and towards you, being carful to work it free of the margin release lever
If your carriage is sluggish, the escapement arm may be the culprit. You need to make sure it's clean and moving freely. To take a look, fold up the typewriter. The underside of the carriage has a cover over the mechanisms. Remove the screws on both ends of the cover and lift it off.
Everything underneath here needs to be really clean. Use a solvent like mineral spirits to flush and clean the area. Swabs and/or small paint brushes are helpful as well. The escapement arm in particular needs special attention. Here it is shown in red.
It pivots on a shaft at the left while the tip on the right moves up and down in a slot. It must move freely for proper carriage advancement. To test this, detach the spring on the left side where it hooks into 1 of 3 positions, usually the center one. Now, lift the right side of the arm to the top of the slot, and let go. It should immediately fall freely and completely down. If it doesn't, that's a problem. You can clean the arm in place, but there may be unreachable grit on the pivot shaft that no amount of flushing will remove. The arm can be carefully removed for cleaning.
Remove both nuts and the washer on the shaft, and unhook the spring if you haven't already. Now slowly slide it off the shaft, being careful not to bend the tip or the slot. You will have to finesse the arm a bit to get it completely off. It seems to work best with the tip toward the top of the slot. Once the left side clears the shaft, slide the arm carefully out of the slot to freedom.
Soak the whole arm, nuts, and washer in the solvent of your choice and brush/wipe them clean. To reinstall it, finesse it back into place, then replace the washer and first nut onto the shaft. Tighten the nut to the point where the arm will not move up and down. Now, loosen it just enough that the arm will freely drop from top to bottom. When you've found the sweet spot, hold that nut in place while you replace/tighten the second nut.
If the escapement arm still won't move freely, the tip could be binding within the slot. If so, you'll have to gently widen the slot where it's binding, using a screwdriver or other tool. Another option is to very slightly narrow the tip of the arm with a Dremel grinder tool. Choose whichever path you feel most confident in.
Now, test your Corona again. Hopefully it's smooth typing from here on out!