This black plastic key was used on all models from about 1955 up through 1973.
Hello Duane, As an avid reader of Boxerworks forums and your excellent articles, I hope you will not mind my writing to you directly, regarding your article on switches & keys. It has come to my notice whilst working on these older bikes for 20 odd years that there is a problem that has not been mentioned at least as far as I know.
It is that modern replacement black keys are made wrongly, and will cause early headaches & heart aches to those who go to the trouble & expense of fitting new parts above circuit board. The new keys only grip in the keyway slot by approx half of its depth. This will cause parts to have a much shorter life. Think of bending those tabs too often. If you compare an original black key & the new replacement you will find that the upper groove for the balls to click into are approx one MM TOO FAR from tang on key which actually turns the switch. This is bad work, as there is not a lot of grip even if fully engaged. This is easily checked on the workbench by placing the key fully into brass part and looking into hole for the steel ball to see how far out of line the groove is. It should be dead center. I have also reclaimed the brass part which has the keyway, by silver soldering up the worn slot, & remachining it to original. It works well & is not hard to do.
I hope you can use this to pass on to others. Best regards from Geoff Curtis in Australia.