To the right of the platen there is a collet that is held in place by a threaded screw, sometimes two. Loosen the screw/screws so that the collet moves freely.
- Lock the carriage using the carriage-lock lever above the ribbon selector switch. (or using the different carriage lock mechanism if working on a Halda P).
- Using your left hand, press the carriage-return lever all the way to the right while gripping the left carriage knob firmly. (Holding the carriage-return lever helps to prevent the platen from turning during the following step.)
- Using your right hand, grip the right carriage knob and turn it counter-clockwise to unscrew and remove it.
On the left carriage knob, loosen the two screws that secure it to the platen rod. Remove the knob.
Disengage the toothed platen gear by moving the release lever fully forward. This is necessary to allow the easy removal and reinstallation of the platen. If it isn’t disengaged prior the the removal and replacement of the platen, the line advance mechanism may be damaged.
From the right side of the carriage and using some long-nosed pliers, reach into the cavity revealed by the removal of the knob and withdraw the platen rod.
The platen rod is shown here only partially withdrawn. Withdraw it completely and set it aside, then move the platen release lever forward to disengage the feed rollers.
Unlock the carriage and move it all the way to the right. It should then be simple to lift the platen from the right side and remove it from the carriage.
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Reinstallation tips: It can be a little finicky reinserting the platen rod. Use the back of a pencil to hold it in place while reinstalling the left carriage knob. Remember to correctly reinstall the collet.
Removing the platen is useful for reasons other than replacement: It makes cleaning or replacement of the feed rollers possible, allows cleaning other components not otherwise accessible, and also the observation and adjustment of mechanisms normally hidden.