The butterfly shaft rear support bearing seems to have disappeared from my lower plenum. Also, the cam that actuates the butterflies was fairly worn.

Here is the tale of my repair...

Here is the bronze drill bushing I used. It is a 19/64", I bought it from McMaster-Carr.




I used 24 hour JB-Weld to glue it in. I used the shaft itself to position the bushing, and I mounted 3 of the butterflies back on the shaft to help position things correctly.
Every now and then I'd turn the shaft back and forth to make sure I didn't accidentally glue it in.




The hole in the cam for the diaphragm actuator was in pretty bad shape.




I had a plan...that involved some experimentation...




I used a nylon flange bushing to position a washer on either side of the cam, in approximately the original hole location.
I clamped the washers with vise-grips, removed the nylon bushing, and then TIG welded them.
I didn't weld the whole circumference just in case I needed to undo it...but I think it's more than adequate as is.










It all seems to work fine!

I don't have a clip or keeper of any kind on the shaft of the actuator. The way the shaft fit through the nylon bushing, it actually feels like it has a bit of a detent when it comes out the other side.