I had mine apart as a had to use the mirrors from the 3rd gen and mounting bracket from a 2nd gen to get remote mirrors and deicer on my 02 3500. It's a tough job and will take you 8 or more hours to disassemble, repair and put back together.
There is no adjustment on these mirrors. There is a crush collar that holds the spring tension on a metal shaft (pivot) that keeps the mirror head and and the swing arm tight. Taking the mirror and arm housing apart is a real pain; you will need a couple of thin screwdrivers to pry them apart. You will have to take the entire mirror assemblies off the truck, take them apart get a socket larger than the shaft and hammer the crush collar tighter at both pivot points. If it works, good; if not, you may have to pry the crush collars off, bend them a little straighter, then hammer them back on with the socket.
Good luck and let me know how it works.
Wiredawg