Mech engine control

[cygnus x1]

Not sure where to post this question. I have the side mounted (cockpit) Morse two lever control on a '80 Catalina C30. The PO left this a hot mess. I'm sure it is missing parts, as it has a PVC tube (not the chrome) cover over the trans shift lever. There is nothing holding the shift lever housing to the hex shaft, other than a bunch of washers stacked up between the end plate on one side and throttle lever housing on the other.

My problem is there is considerable friction between the shift lever and the throttle, which causes the throttle lever to move forward and increase the engine RPM, when shifting from reverse to neutral, or neutral to forward. Not the best thing when your trying to dock.

My question is what holds the shift lever housing to the hex shaft? I see a grove cut in the hex shaft section, where I presume a pin or set screw is supposed to mate to the grove. I do not see a threaded hole in the shift lever housing for a pin or Allen set screw (like used on the throttle lever housing)?

I have read where this model Morse was supposed to have removable levers? The throttle level snaps in and out, but the shift lever is frozen in place to the housing? Does the shift lever somehow hold it on the hex shaft? Without a pin or set screw, it is sliding back and forth on the hex shaft section.

I called Catalina, but they had no information other than it was a Morse control. They could not even tell me the model number? I do not see a model number anywhere on the control.

I know this is a lot to read through, but if you own one of these controls, maybe you had yours apart and can explain what I'm missing???