So, since the handlebar was squeaking so much while peddling, I looked down and can see the aluminum bar moving around within the plastic base, time for repair.
Drilling the pop rivets was easy, and pulling the base off as well.
Removed the screw holding the retaining cord.
Pulled off the base!
No adhesive in the base, only on the aluminum
Very brittle lines of adhesive.
So the question is what adhesive is the best, two part epoxy, contact cement, Liquid Nails (HomeDepot)?
The adhesive obviously did not bond to the plastic, and it became brittle and fractured to failure in less than 15 months from purchase, allowing gaps to form and increase with constant cycling. I am sure the plastic base is flexing within the board's socket, and the handlebar acting as a levered fulcrum, creating high stress.
I am leaning towards contact cement, it is flexible and tacky, does not get brittle. Does a great job on deck pads.
Thanks for anyone's help!