If you have the revised (redesigned) door mirors with the longer arms, then I believe there are no aftermarket alternative.
If you have the older design mirror then fit the Librand stainless version and bin ( sell) the Morgan units.
The issue in the Morgan mirrors appears to be the spring that holds the mirror arms in position, they are either too weak
in manufacturing or age and become weak. The idea ( design) of the spring is to allow the door mirror to fold back if hit.
