There are 2 types of couplers ,
one style has the hockey stick coming out of the gearbox which goes into a round metal piece , then a round “rubber piece” in the center , then the metal front section has a hole for the shift rod to slide into ,
the other style is rectangular with a metal cage that holds rectangular rubber pieces that a screw goes thru , the shift road has a metal sleeve on the end where the screw goes thru ,
There have been some real junk couplers thru the years, if there are German ones get one ,
Simple to change yourself …..