Weapon of Choice: 1978 Brother Charger 11 #K83712885
In 2017, I shrinktubed the platen, along with a couple others.
To adjust ring & cylinder on a JP-1 is done by loosening these two screws on both sides of the carriage rail and moving the rail back enough to account for the thicker platen. You check this by rolling in a sheet of paper and placing another slip of paper between a middle typebar slug raised up to the platen and ensuring that the typebar pressed against this paper allows the slip of paper to be pulled out without much resistance. To ensure Platen Parallel, do this test on both sides of the platen to ensure that the pull resistance is equal on both sides. This adjustment moves the entire carriage assembly (and the platen) further away from the point of typeslug impact, and because the carriage shift stops stop on an inclined plane, the On Feet will be lower than before the adjustment, and will have to be re-adjusted.
Oddly, none of this is covered in the factory service manual and I had to figure it out myself – but because I have enough documentation on how this works on other, similar machines, it wasn’t difficult to locate the adjustment points and suss out what needed doing. I use a produce rubber band to hold the typebars up while I remove the whole typebar rest bracket to work on it. The rubber rest is just glued onto this bracket, so pull it off and rubber cement or glue your replacement strip in it’s place. You do this while the bracket’s out of the machine both because it’s easier, but you also don’t want to drip glue down into the worky bits.
Charger 11 passes the sniff test.
The Joe Van Cleave method of silencing the typebar return spring.