When working to reassemble the radio I noticed that the shaft coupling for the final control was slipping and further discovered that this plastic coupling threads were stripped. Threaded plastic can be rather delicate so a repair was in order.

To repair the coupling I removed the screws and disconnected the shaft coupling.

Figure 1. Removed Shaft Coupling

To repair I marked two new hole and thread locations 180 degrees away on the opposing side of the coupling. Note the holes do not need to be directly in line with each other just some what close. After choosing the correct fastener size I selected the correct drill and thread tap and drilled and tapped new holes.

Figure 2. Coupling with newly threaded holes

Next I reinstalled the coupling and reinstalled the set screws. I noticed that the screws seemed to hold into the threads much better than before.