How to Repair Underwood Typewriters
See also the Quick Reference to locating Trouble section with more than 200 points to check in order to fix most common problems, with pictures to locate them.
I'm scanning and putting in
hypertext format an old Service Technical Manual:
The first step taken in overhauling, cleaning or rebuilding a typewriter, is to take the machine completely apart, down to the base or main frame.
It is not necessary to take out the key levers, key lever locking rod (W Plate 2), back space key lever, or other parts that do not interfere with the cleaning of base.
Keep the screws and small parts in a box so that they will not get lost or mislaid. Remember the screws as they are taken out so that they can he replaced in their respective places.
Brush the loose dirt out of base and from parts. Use a pan large enough to take base and have brushes fur cleaning and soak and clean thoroughly all parts in gasoline with about 5% oil mixed with it.
The type bars and segment can be cleaned in alcohol this will insure a better job In cleaning the segment make sure that there is no dirt or grit left in the slots.
After cleaning blow through the slots, this will take out the alcohol and any dirt there is with it. On parts where the dirt is crusted on and cannot be taken off with a brush use a scraper and repaint the part with dull black paint.
After all the parts have been cleaned wipe off, the gasoline as much as possible. They will collect dirt and - dust if this is not done. If the key levers (A Plate 2) or key lever links (C Plate 2) look old and the machine is to be rebuilt it is a good plan to repaint them with the dull black, also any parts that show.
It is seldom necessary to remove the key levers except in a case where the casting is broken and should be replaced. These come out by loosening retaining plate under machine held in place by two screws (O Plate 2). All the tension screws (N plate 2) should be loosened to take tension off springs before removing the key levers.
After all parts are cleaned and dried start to assemble and readjust the parts.
The key levers (A Plate 2) are all numbered from 1 to 42 on standard machines and from 3 to 40 on No. 4 machines.
These are placed in position key lever tension springs (L Plate 2) are placed in holes in base over key lever tension screw (N Plate 2) When a key lever is in position, see that it is perfectly free m the slot of comb at front of machine (S Plate 2).
The key lever should not rub on either side of comb slot and should go up and down with the slightest tension placed on spring. See that the lever is parallel with comb slot and not twisted. Key levers that rub or stick in any way will cause a sluggish action to type bar when operating machine.
In freeing the key levers use a bender which is a round piece of steel with slot in the end to take key lever. This applied at the end of the key lever near point (X1 Plate 2), and the key lever is twisted one way or the other until free and parallel with slot in comb. If the lever cannot be freed with the bender three prongs or nine prongs can be used to throw the key lever to one side or the other until free.
Sometimes the slots in the comb will be closed up so that the opening is too narrow, this will cause a bind also and they should be pried apart with a screwdriver but not so much that the lever in the next slot will bind.
After all the key levers are in place the tension should be tried on each key lever individually. This is adjusted by adjusting the tension screw (N Plate 2) so that the key lever when depressed will come back with a small click to the top of comb slot and stay there.
It should not come back with a dead spongy action. If it is found that by using three prongs or nine prongs that the key lever is still spongy in action, it will probably be found that the end of key lever is hinging in bracket and will have to be filed down a little.
In taking the key lever out loosen retaining plate screws (H Plate 8). This plate holds the keylevers in position so that they cannot jump out during operation of the machine fake all the tension off the key lever tension spring and grasp the key lever with pliers at the end and pull towards you and up at the same time. The lever should come out readily.
When replacing the key lever set the end in position over slot and use pliers pulling towards you and forcing down. It should snap back into position in the bracket. The tension spring should be in place before placing key lever.
After key lever is in place set spring over lug with spring hook. Now tighten tension screw until the key lever snaps up to the top of comb and stays there. Loosen the key lever tension screws retaining plate (R Plate 2) whenever adjusting tension screws. The screws are set so that the Rat side comes against this plate and the plate is to keep them from working out.
This plate is fastened in with three screws (M Plate 2) which have springs over them. As the key levers are important factors in the action of a machine, particular attention should be paid in seeing that they are perfectly free, and that the tension is as light as possible without having the key levers drop away from the top of slot in comb.
The black space key lever (H Plate 10) and the tabular key lever (I Plate 10) have pins that come down on rests located on key lever comb. See that the levers come down solid and do not go by. If they should go by the lugs are bent in or out.
The backspace and tabular key levers should be tried to see that they do not bind. In trying the hack space lever take the screw at (1 Plate 8) out and raise back space key top. It should drop hack without the slightest bind. The tension on the tabular key should be about the same as that on the key levers. The hack space lever can be freed with the bender or three prongs.
Whenever it is found that the key tops are loose on key levers, they can be made solid by soldering or wedging in place with prick punch.
The key ring glass and paper should be taken out before doing this. Old key rings and dirty key papers should he replaced by new, if the machine is being rebuilt. Anyways, have the keyboard looking neat and new.
The key tops should all be on a straight line with one another (J Plate 10). Do not have one up and another down. This is adjusted with peering pliers applied under the machine. Peer the lever on the top to throw it down, and on the bottom to throw it up.
The typewriter should stand on its back as in Plate 8, when freeing key levers, or making other adjustments under machine.
(to be continued...)